To evaluate and understand the prevalence of HPV genotypes and characteristics of female populations in specific areas and the relationship with cervical lesions, which can effectively guide cervical cancer screening and formulate HPV vaccine prevention strategies.A total of 77,443 women who visited gynecological clinics and underwent health examinations in the Second Affiliated Hospital of Zhejiang University School of Medicine during 2016–2020 were enrolled in this survey. Cervical samples were collected for HPV DNA genotyping and cervical cytology testing. Cervical biopsies were performed for patients with visible cervical abnormality or abnormal cytological results.P < 0.001). The five most common genotypes in Zhejiang Province were HPV 52, 58, CP8304, 16, and 51 . HPV infection was age-specific, with the highest infection rate in the age group ≤ 20 compared to other age groups (P < 0.001). HPV infection was also season-specific, with the highest infection rate in spring or winter. The main HPV infection mode was single infection (P = 0.004), but patients ≤ 20 years old were more likely to develop multiple infections (51.0%). HPV 16, 52 and 58 were the main genotypes that caused cytological abnormalities and HPV16, 18, 56, 58 and 66 were independent risk factors for cervical lesions . Further analysis found HPV 16 and 18 were the main genotypes that cause cervical cancer histological abnormalities and were independent risk factors for cervical cancer .The results showed the 5-year overall positive rate was 22.3%, of which the gynecology clinic group had significantly more positive results compared with the health examination group (This article analyzed the prevalence of distribution characteristics of HPV infection and revealed the corelation between HPV infection and cytological and histological abnormalities. Comprehensive results of this survey will help Zhejiang Province to formulate public health policies and provide evidence for future selection of specific HPV vaccines. As the fourth most common cancer among women worldwide , cervicaPersistent human papillomavirus (HPV) infection is a significant factor in causing cervical cancer . At presHowever, cervical cancer is a highly preventable and curable cancer; primary prevention and screening are the most effective ways to release the burden of HPV infection and reduce the mortality of cervical cancer. It is noteworthy that the promotion of the HPV vaccine has made a significant contribution to the prevention of cervical cancer –9. The HDue to differences in climate, living habits, and population distribution, different regions show different infection rates of HPV in China , 12. UndThis article collected data from patients who have undergone HPV screening in the Second Affiliated Hospital of Zhejiang University School of Medicine’s health examination center and gynecological clinic between 2016 and 2020. The study analyzed the prevalence of HPV infection, the distribution of genotypes, and the characteristics of age-specific and season-specific infections. At the same time, the association of HPV infection with histological and cytological results were observed. This study aimed to provide a reference for the early prevention, detection, and control of cervical cancer, and a guide for the promotion and application of targeted vaccines for women in Zhejiang Province.The Second Affiliated Hospital of Zhejiang University School of Medicine, as a well-known top hospital in the capital city of Zhejiang Province and one of the designated hospitals for cervical cancer screening, has huge daily outpatient visits and diverse patients, has huge daily outpatient visits and diverse patients. In this retrospective study, in order to obtain more accurate and reliable data, we collected large-scale data on female patients who attended health examination center and gynecological outpatient clinics of the Second Affiliated Hospital of Zhejiang University School of Medicine during 2016–2020. All patients were divided into two groups: health examination group (HEG) and gynecological clinic group (GCG). This study was approved by the Ethics Committee of the Second Affiliated Hospital of Zhejiang University School of Medicine. The review committee waived the need of patients’ consent due to anonymous analyses of the data. The management and publication of patient information in this study was strictly in accordance with the Declaration of Helsinki, including the confidentiality and anonymity.Inclusion criteria: (1) history of sexual activity at any age; (2) voluntary HPV test; (3) had not had sexual intercourse, nor used vaginal drugs in the previous 48 h; and (4) had not been vaccinated against HPV.Exclusion criteria: (1) patients with other infections or autoimmune diseases; (2) pregnant women; (3) patients who had undergone cervical surgery or hysterectomy; and (4) patients who had undergone immunosuppressive therapy.The clinician used a speculum to expose the cervix and wipe off excessive secretions with a cotton swab. A cervical brush was rotated slowly in one direction for 6–7 times to obtain sufficient cervical epithelial cells; this was repeated twice. One of the cytology brushes was used for HPV-DNA detection, and the other brush was placed in preservation solution for a ThinPrep cytologic test . All samples were stored at 4 ℃ and tested within 48 h.The PCR-reverse dot blot hybridization test was used for HPV DNA genotyping detection. The YN-H16 constant temperature hybridization instrument, cervical exfoliated cell collector, and HPV genotyping detection kit were provided by 21 HPV GenoArray Diagnostic Kit (HBGA-21PKG)  and GenPlex® microfluidic automatic nucleic acid detection . HPV DNA extraction, PCR amplification, hybridization, and result interpretation were performed according to the manufacturer’s instructions.It is worth noting that the position where the blue spots appear on the membrane strip relates to genotype information marked on the corresponding position. If only one genotype site has blue spots, it indicates a single infection of the corresponding genotype; if multiple genotype sites have blue spots, it indicates a mixed infection of the corresponding genotypes.Two types of HPV genotype tests were carried out clinically, HPV-DNA 21 and HPV-DNA 24, and included 18 high-risk HPV types , and seven low-risk HPV types  [Cervical slides were analyzed with TCT and diagnosed by two experienced pathologists. The TCT results were classified according to the Bethesda 2001 criteria , includiA cervical biopsy was performed for patients with visible cervical abnormality or abnormal cytological results. The histology results were graded by two professional pathologists according to the pathological diagnosis standard criteria, including no lesions, cervical intraepithelial neoplasia , and cervical cancer.P < 0.05 was considered statistically significant.All statistical analyses were performed using R software 3.5.1, Excel 2019 and SPSS 22.0 software . Numerical data were expressed as a percentage (%). Pearson's χ2 test and binary logistic regression analysis were performed to evaluate the significance of the difference between the specified groups. P < 0.001).In total, data was collected from 77,443 HPV screening tests from the HEG n = 29,216) and GCG  between 2016 and 2020. Among them, 17,234 HPV-positive patients were screened and the average infection rate over 5 years was 22.3%. The annual HPV infection rates in HEG were 13.2%, 13.6%, 15.3%, 13.6%, and 12.4%, and the 5-year average infection rate was 13.6 ± 0.9% (Table 6 and GCGP = 0.063), it can be seen that during 2016–2020, the HPV infection rate in summer was the lowest; the HPV infection rate in winter or spring was the highest.The change trend of HPV infection rate from 2016 to 2020 in HEG and GCG can be observed by comparing the data in Table The distribution of infection rate for each genotype over the 5-year period is shown in Fig. In HEG, the top five genotypes were HPV 52, 58, CP8304, 16, and 53, and the positive rates were 23.5%, 11.0%, 10.8%, 9.0% and 9.0% respectively. In GCG, the top five genotypes were HPV 52, 58, 16, CP8304 and 51, and the infection rates were 24.0%, 13.2%, 12.5%, 9.5%, and 9.5%.P < 0.001).Among the 77,443 patients included in this study, patient’s ages ranged from 10 to 98 years old with an average of 41 ± 11 years. All patients were divided into seven age groups . HPV infection rates in different age groups were analyzed as shown in Fig. We further evaluated the positive rate of each genotype in each age group to explore the age-specific distribution of genotypes.P < 0.05). The distribution of HR-HPV and LR-HPV in different age groups is shown in Fig. It can be observed that, regardless of age group, HPV 52 had the highest positive rate (P = 0.004). The infection rate of single infections reached its peak in the 41–50 group. Regarding multiple infections, the main manifestation was a double infection. The age group of ≤ 20 accounted for the largest proportion.Table It is worth noting that in the age group ≤ 20, the probability of multiple infections (double + triple + quadruple + fifth infections) was higher than single infection, which accounted for more than 50%.P < 0.05).The process of obtaining cytological test results and pathological biopsy specimens is shown in Fig. A total of 1637 HPV-positive patients were pathologically diagnosed after vaginal biopsy. Among them, 642 cases had histological abnormalities (39.2%).P < 0.001; OR = 2.226, P = 0.001; OR = 1.638, P = 0.009; OR = 1.421, P = 0.013); patients infected with HPV16 or 18 are at increased risk of developing cervical cancer from cervical epithelial neoplasia .The distribution of HPV genotypes in different histology results is shown in Table In May 2018, the Director-General of the World Health Organization (WHO) called for action toward achieving the global elimination of cervical cancer .ThereforAmong the participants in this study, the 5-year total HPV positive rate was 22.3%, similar to two other surveys carried out in Zhejiang Province , 20. AccSince this study included patients from both the health examination center and gynecology clinic, it is a more representative reflection of the overall HPV infection situation. We found that the overall infection rate increased during the 5-year period, which may be due to increased awareness of prevention and the popularization of HPV screening, but it is also possible that, with the development of society and economy, young people's sexual habits have changed and they are sexually active earlier and have multiple partners.Previous studies had shown that seasonal changes strongly affect biological functions, including susceptibility to infectious, metabolic, inflammatory, and malignant diseases , 24. HPVA large number of studies have shown that HPV infection is significantly age-specific , 29. TheThe age-specific prevalence curve of a single HPV infection presented a unimodal distribution, reaching a peak in the group aged 41–50; the groups ≤ 20 years and > 70 years were quite low, which was similar to the findings by Shanxi and Beijing , 34. ComHigh-risk HPV infection is a primary factor in precancerous lesions and cervical cancer. We found that the distribution of high-risk HPV genotypes is directly related to the severity of cervical cytopathology. By analyzing the cytology results of 3,912 patients, it was found that regardless of AGC, ASC-H, ASC-US, LSIL, or HSIL cytology samples, HPV 16, 58, and 52 were always the major type, with variations in rank varied, which was consistent with the data in other studies , 38. FurAmong the population with abnormal histological results, the distribution of HPV was also different. But, in general, similar to the cytological results, we observed that in CIN 1, 2, and 3, HPV 16, 58, and 52 were always the major type. Additionally, with the increase of the histological lesions grade, the infection rate of HPV 16 also increased, especially in cervical cancer (58.33%). Multivariate logistic regression analysis showed HPV16 infection is closely associated with the severity of cervical intraepithelial neoplasia and cervical cancer. Moreover, HPV 18 was also the most common oncogenic type associated with cervical cancer, which was similar to previous studies . PreviouIt is our belief that the promotion and popularization of bivalent and quadrivalent vaccines has caused a decline in the infection rate of HPV 16 and 18. However, the overall HPV infection rate is still increasing; prevention of cervical cancer still has a long way to go. Although there are currently three preventive HPV vaccines  in use globally, the WHO has not given biased recommendations for these three types of vaccines . With reThere are some limitations in this study: First, due to sampling error, operation error, or other reasons, the results of the ThinPrep cytologic test may be over-diagnosed or missed. Second, the lack of detailed information on the geographic, socio-demographic, and behavioral characteristics of the study population prevents assessment of these characteristics on the HPV infection rate. Finally, the absence of data from other areas in Zhejiang Province means that these results might not be representative of all women in Zhejiang; a larger and more representative population is recommended for future research.In summary, this article analyzed the prevalence of HPV over 5 years and studied age distribution characteristics of different genotypes and single and multiple infection types. Moreover, the correlation between HPV infection and cervical lesions was also observed, which will help Zhejiang Province formulate public health policies and provide evidence for the future selection of specific HPV vaccines.


The HPV vaccine has shown sustained efficacy and consistent stabilization of antibody levels, even after a single dose. We defined the HPV16-VLP antibody avidity patterns over 11 years among women who received one- or three doses of the bivalent HPV vaccine in the Costa Rica HPV Vaccine Trial. Absolute HPV16 avidity was lower in women who received one compared to three doses, although the patterns were similar (increased in years 2 and 3 and remained stable over the remaining 8 years). HPV16 avidity among women who were HPV16-seropositive women at HPV vaccination, a marker of natural immune response to HPV16 infection, was significantly lower than those of HPV16-seronegative women, a difference that was more pronounced among one-dose recipients. No differences in HPV16 avidity were observed by HPV18 serostatus at vaccination, confirming the specificity of the findings. Importantly, point estimates for vaccine efficacy against incident, six-month persistent HPV16 infections was similar between women who were HPV16 seronegative and seropositive at the time of initial HPV vaccination for both one-dose and three-dose participants. It is therefore likely that this lower avidity level is still sufficient to enable antibody-mediated protection. It is encouraging for long-term HPV-vaccine protection that HPV16 antibody avidity was maintained for over a decade, even after a single dose. As a measure of the functional maturation of the humoral immune response2, avidity depends on the intrinsic affinity of the antibody for the antigen, the valency of the antibody/antigen interaction , and the structural arrangement of the interacting components. Increases in antibody avidity after vaccination with protein antigens is often observed, the result of somatic hypermutation in the variable regions of immunoglobin genes, which normally occurs in lymph node germinal centers (GCs). However, there is a paucity of information on the changes in the avidity of the polyclonal antibodies induced by vaccines over the course of many years or the influence of booster doses or immune responses from preexisting infection on the strength and durability of the avidity.Antibody avidity is a measure of the collective binding strength (affinities) of a polyclonal antibody response to a defined antigenTM) result in durable antibody levels against the vaccine-targeted HPV types; this is correlated with durable protection against infection by these types and as well as several cross-protected types3. The most recent data from CVT have shown that this degree of protection is sustained for over a decade following initial vaccination5. Specifically, there is evidence demonstrating that the anti-HPV16 or 18 antibody levels did not decline between years 4 and 11 and were significantly higher than those induced by natural infection, regardless of the number of vaccine doses received, although one-dose titers continued to be significantly lower than two- and three-dose titers4.Clinical trials of the HPV virus-like particle (VLP) vaccines such as the Costa Rica HPV Vaccine Trial (CVT) provide an opportunity to address these questions, because it has demonstrated that three, two, or even a single dose of the bivalent HPV vaccine 6. At Year 4, a small difference in HPV16 antibody avidity between women who received one or three doses of the HPV vaccine was observed, which remained stable for both dose groups at Year 73. These findings suggested that booster vaccine doses provide only a small increase in long-term anti-HPV16 antibody avidity.Previous publications from CVT have evaluated antibody avidityIt is of considerable interest to measure the evolution of affinity during the initial years after single-dose vaccination and to further define the long-term durability of the avidity response by dose group. With more than a decade of active follow-up of HPV-vaccinated women in our trial, we assessed HPV16 antibody avidity out to 11 years post-vaccination among women who received the recommended three-dose HPV vaccine regimen and compared that to women who received only a single dose. In addition, we examined the effect of previous or current HPV16 infection on HPV16 antibody avidity to the vaccine’s VLP antigens after vaccination, since the HPV vaccines are widely administered to sexually active young women. Our study aimed to increase our understanding of the antibody response to the HPV vaccine, shed light on how a single dose of the bivalent HPV vaccine provides durable protection against HPV infection, and provide predictions on how future virus-like display vaccines may perform.We demonstrated representativeness of our sample selection and comparability in characteristics between one-dose and three-dose groups at study enrollment and thus first HPV vaccination with respect to age, HPV16 serostatus and HPV18 serostatus, and HPV DNA status  (Supplementary Table p-for-trend for between years 4 and 11 was 0.28 (Table For one-dose recipients (198 women with 747 serum samples), Geometric Mean of the Avidity Index (GMA) ranged from 2.39 to 2.81 for years 1 through 11 ; at the peak of the avidity response, in Year 3, the ratio was 0.94 (0.89–1.00) (Table For three-dose recipients (321 women with 1115 serum samples), GMA ranged from 2.87 to 3.07 during years 1 through 11. The greatest increase in avidity was 4.0% in Year 2. Avidity remained stable during years 4 through 11, measuring 3.02 both in years 4 and 11; the In addition to the GMAs being stable over time in both the one-dose and three-dose participants, the avidities for individual participants similarly tended to be stable over time . These ratios remained relatively constant throughout the study period , the GMAs in baseline seropositive subjects were 0.78 (0.53–1.15) and 0.97 (0.79–1.20) in one-dose and three-dose recipients, respectively, which are substantially lower compared to post-vaccination  and HPV16 seropositive  at the time of initial HPV vaccination. In the smaller one-dose group, vaccine efficacy was 100% among both the HPV16 seronegative (95% CI 60.1–100.0%) and HPV16 seropositive (95% CI −171% to 100.0%) women at the time of initial HPV vaccination, although, statistical power for seropositive women was limited due to small sample size  for the one-dose group and 0.14 (0.01–0.27) for the three-dose group , the subjects were younger (aged 10–18 years), the use of a different chaotrop in the ELISA (urea vs guanidine hydrochloride), and the avidity measurements were determined for a single concentration of chaotrop rather over a range of concentrations as in our study, which might permit detection of subtler differences. Pasmans et al.10 also reported no difference in antibody avidity to HPV16 L1 at 5 years post-vaccination in girls aged 12–16 years who received one, two, or three doses of CervarixTM an average of five years earlier. However, avidities were also determined for single concentration of a different chaotrope (ammonium thiocynate). Perhaps more importantly, the ages of the one and three-dose CervarixTM recipients in Pasmans’ work differed, 12 and 16 years respectively, whereas the vaccinees in our study were the same ages. This could influence the avidity results in two ways. Antibody responses to HPV VLPs are in general superior in children prior to puberty. It is reasonable to suspect that this difference may extend to avidities. In addition, Pasmans et al. did not stratify by HPV16 serostatus at baseline. It is reasonable to postulate that there are more HPV16 seropositives in the 16-year-old three-dose group than in the 12-year-old one-dose group. Our finds document that avidities tend to be lower in seropositives at baseline, so differential seropositivity in the three-dose group would differentially lower their mean affinity, the net result that they could appear to be the same as one-dose recipients.There have been other investigations into HPV vaccine-induced avidity, albeit with different findings, likely due to differences in either study or laboratory methodology. Sankaranarayanan et al.4. At the individual level, avidities within each participant similarly tended to be stable over time. As only a small minority of the women were likely exposed to HPV16 virus during the trial4, the ongoing high avidity is attributable to the durability of the vaccine response.The avidity that developed from one dose continued to increase over the first three years after vaccination, which is a year longer than it took to reach maximal avidity after three doses. The average levels of avidity during years 3 through 11 remained 5–10% lower after one dose compared with three doses, a smaller difference than the differences in antibody levels after one versus three doses11. Alternatively, the gradual increase in avidity might be attributable to the preferential survival during this period of plasmablasts that received the strongest signaling through their B cell receptors12, i.e., had the highest affinity for the VLPs, after which any survivors would have become established, long-lived plasma cells (LLPCs). Regardless of the mechanism, the sustained high avidity levels of HPV16 antibodies through year 11 make it likely that once the peak level of avidity has been reached for a given woman, her LLPCs continue to produce consistent antibody levels whose avidity is also consistent.There are at least two possible explanations for the continued affinity maturation over several years after only a priming dose. One could be that there is prolonged retention of the vaccine antigen in the GCs. Although complete denaturation or degradation of a typical protein antigen might be expected over a shorter timeframe, HPV VLPs are exceptionally stable structures, and their polyvalency might promote their extended retention on follicular dendritic cells13.Women who were HPV16 seropositive at vaccination had lower avidities in follow-up: the GMA ratio for the HPV16-seropositive women vs. the HPV16-seronegative women was significantly lower (0.66) for one dose than for the three doses (0.82). The lower HPV16 avidity levels appear to be antigen-specific, rather than being attributable to a more general immune perturbation induced by mucosal HPV infection, as the HPV16 avidity for women who were HPV18 seropositive at first HPV vaccination was similar to the HPV18 seronegative women. Therefore, it is likely that the prior low-level mucosal exposure of a specific antigen substantially influences the subsequent quality of the antibody response upon parenteral re-exposure to what is essentially the same antigen. The HPV18 results also serve to distinguish the response to HPV vaccination from the concept of “original antigenic sin” where, as in the case of influenza infection, prior exposure to one virus strain prevents efficient induction of antibodies to unique epitopes from a distinct, but antigenically related, strain14. This observation suggests that the antibodies resulting from infection may generally be of lower avidity, despite the fact that HPV16-VLP-specific IgG genes from mBCs induced by infection and vaccination had similar numbers of somatic mutations14 A second possibility is that the avidity levels measured after vaccination of HPV-exposed women reflect the sum of the lower avidities of the antibodies produced by LLPCs generated from naive B cells after infection and those of higher avidities generated after vaccination. A subset of women do appear to generate LLPCs after infection, as indicated by the persistence of serum antibodies after the apparent clearance of infection15. Mechanistically, this might appear to be the simplest explanation. However, the GMTs after natural infection are 10-fold lower than those seen at the plateau phase after single-dose vaccination and 40-fold lower than that after three doses. It is difficult to reconcile the apparently small contribution of infection-induced antibodies to the total antibody levels and the substantial effect on the avidities, especially for the three-dose recipients.The mechanism responsible for the reduced antibody avidity after prior mucosal exposure is uncertain. One possible explanation is that low-avidity memory B cells (mBCs), preferentially generated after mucosal infection, can be driven into LLPCs after secondary exposure to antigen by parenteral vaccination, but remain “imprinted” with a generally lower avidity B cell receptor, despite presumably having participated in a secondary GC reaction and therefore a second round of somatic hypermutation. A previous study found that most of the HPV16-VLP monoclonal antibodies (MoAb) generated from infection-induced mBCs were non-neutralizing, while most of the MoAb generated after vaccination were strongly neutralizing16. Therefore, one explanation for our observations is that the induction of LLPCs largely follows the same pathway initiated by an interaction with naive B cells after priming and boosting. Consistent with this hypothesis, the recruitment of cognate mBCs into secondary GCs was limited in mouse models of vaccination and influenza infection. Rather most of B cells recruited into the secondary GCs appeared to be antigen inexperienced, likely naive, B cells. Since it is widely held that B cells much go through a GC reactive to evolve into LLPCs, these findings imply that most of the durable antibody responses after booster immunization would be derived from naive B cells17.The hypothesis that LLPCs after boosting are mostly generated from naive B cells, rather than lower avidity mBCs, is supported by several observations. First, the plateau levels of antibodies maintained after VLP vaccination are almost additive by dose. We repeatedly observe that, in the plateau phase, HPV16-VLP antibody levels after three doses are only about fourfold higher than after one dose. Second, the quality of the antibodies after priming and booster doses is similar, as measured here by avidity and previously by the ratio of neutralizing to binding titers4. Second, one vaccine dose induced a substantial increase in avidity compared to the avidity measured at first HPV vaccination after natural infection. These results indicate that, in addition to quantity, the quality of the antibody response to vaccination remains far superior to that induced by infection. The lower avidity levels that develop after infection may partially explain why the antibody-mediated protection induced by infection appears to be less consistent than protection induced by vaccination, even in vaccinees with low antibody levels after vaccination, e.g., cross-type reactive ones18.It is important to emphasize that, although vaccination of women who were HPV16 seropositive at first HPV vaccination had lower avidities than the seronegative women, this did not translate into suboptimal protection against HPV infection. Specifically for three-dose participants, strong and significant vaccine efficacy was observed against incident, 6-month persistent HPV16 infections after 4 years of follow-up among women who were HPV16 seropositive at first HPV vaccination (VE of 93%), which was similar to that among HPV16-seronegative women (VE of 95%). One-dose vaccine efficacy was also similar by HPV16 serostatus (both VE of 100%); however, results for HPV16-seropositive women were underpowered resulting in broad CIs. These results corroborate our understanding of HPV vaccine protection and durability. First, one-dose HPV vaccination provided to young adult women, some of whom might be expected to have been HPV exposed prior to vaccination, continues to provide strong protection against HPV infection19. However, we did not observe such a correlation here between avidity and antibody titer, as measured our ELISA assay, which has been shown to closely correlate with neutralizing activity16. Instead, the results from an experimental vesicular stomatitis (VSV) model may be more relevant to the HPV vaccine. In the VSV model, increasing avidity contributed to in vivo protection only until a threshold was reached, after which protection was dependent on higher antibody levels but not on higher avidity20. If this model is relevant to the HPV vaccine, even the lower post-vaccination avidity levels that develop in the women who were HPV seropositive at first HPV vaccination are high enough to enable protection.In some situations, a close correlation has been observed between avidity/affinity of vaccine-induced antibodies and their in vitro neutralizing activities, as in the case of an MF59 adjuvated pandemic influenza vaccine4, there is no evidence that prior HPV infection compromises the protection afforded by the HPV vaccines against subsequent exposure. Yet, our findings raise the possibility that suboptimal preexisting immunity generated by other viral mucosal infections might have similarly deleterious effects on the long-term antibody repertoire after subsequent vaccination, which could be relevant for vaccines where the avidity threshold for protection may be higher than for HPV. For example, might asymptomatic SARS-2 infection limited to the upper respiratory mucosa induce low-avidity antibodies that could result in lower vaccine-induced antibody avidity compared with immunologically naive vaccinees? Given our results, it may be prudent to investigate this possibility.Given the exceptionally high vaccine efficacy observed for even a single dose of the HPV vaccineTM; GlaxoSmithKline Biologicals, Rixensart, Belgium) or a control hepatitis A vaccine  in a 1:1 ratio at 0, 1, and 6 months, and were followed for four years in CVT21 (NCT00128661). At enrollment and annual follow-up visits, participants provided a serum sample, and for sexually experienced women, a pelvic exam was performed at which cervical cells were collected for cytology and HPV DNA testing21.Between 2004 and 2005, 7466 women 18–25 years of age in Costa Rica were enrolled and randomized to receive either the AS04-adjuvanted HPV16/18 vaccine  Institutional Review Boards and the corresponding Costa Rican Institutional Review Board; all participants signed written informed consent.27 at the Frederick National Laboratory for Cancer Research, Frederick, Maryland), necessary to control for the concentration of antibody added to the avidity assay, and further restricted to those who contributed two or more serum samples over the course of 11 years (excluding the enrollment visit). After applying these inclusion criteria, our selection yielded 198 one-dose women (with 747 follow-up samples) and 321 three-dose women (with 1115 follow-up samples). We did not evaluate responses to two doses of the vaccine, because most two-dose women in CVT received their second dose after one month, which is an inferior regimen that is not considered to be of public health relevance.For this study, we focused on the enrollment and follow-up study visits at Years 0, 1, 2, 3, 4, 7, 9, and 11. All eight timepoints were included to fully describe the long-term kinetics of antibody avidity over time. Avidity at Year 0  was only evaluated in women who were HPV16 seropositive at first HPV vaccination, providing insight into the avidity of natural infection-induced antibody and the effect of prior infection on avidity responses to the vaccine. Our selection was based on availability of prior IgG ELISA results for HPV16  was added to the samples at various concentrations (0.5–3.5 M) to elute low-avidity antibodies. The concentration of GuHCl that reduced the optical density by 50% compared to sample wells without GuHCl treatment defined the Avidity Index, which serves as the quantitative readout of antibody avidity, specifically measuring the strength of the binding under increasingly stringent binding conditions. There was a narrow range for antibody avidity results and in some cases (N = 134) the assay results were beyond the upper limit of detection for the assay; in these cases, the result was set to the maximum readout value of the assay, 3.51.The assessment of anti-HPV16-VLP antibody IgG avidity was performed as described previouslyn = 94) were randomly selected as laboratory-blinded replicates for quality control; the coefficient of variation was observed to be 5.0% (95% CI: 4.3–5.8%) and the intraclass correlation coefficient was 0.97 (95% CI: 0.96–0.98).Approximately 5% of the samples  using cervical specimens collected at the time of vaccination. The presence of HPV DNA was detected by a polymerase chain reaction amplification with SPF10 primer sets. Using the same SPF10 primer sets, HPV genotyping of 25 HPV types, including HPV16 and 18, was conducted using reverse hybridization on a line probe assay  among SFP10-DNA-enzyme-immunoassay-positive samples.Our study aimed to address three research questions: (1) Does avidity change over the course of 11 years? (2) How does antibody avidity compare between one-dose and three-dose participants? (3) Does the avidity response differ between participants who were seronegative and those who were seropositive at first HPV vaccination ? With the available data, we also evaluated if the relationship between antibody titer and avidity changed over the course of 11 years. Lastly, we examined vaccine efficacy against incident, 6-month persistent HPV16 infections among HPV16 DNA-negative women who were HPV16 seronegative versus HPV16 seropositive at the time of vaccination over the first four years of follow-up among one-dose and three-dose participants.N = 5) who were HPV-seronegative but HPV DNA-positive at first HPV vaccination. We included them in our analysis, as most of these cases were likely transient HPV infections or deposition and would not affect our study on avidity.The main analysis focused on women who were HPV16 seronegative at first HPV vaccination. There were a small number of women (β−1). Generalized Estimating Equations (GEEs) were used in all analyses to account for within-subject correlation. We next compared the avidity between the one-dose and three-dose groups; we reported the ratio between GMAs at each study visit and averaged overall visits. We note these estimates came from regressing log(avidity) on dose group, adjusting for study year as a categorical variable when obtaining the average estimate, and reporting on eβ. We then compared the avidity response of HPV-seronegative women to HPV-seropositive (at first HPV vaccination) women within each dose group; we reported the ratio between GMAs using similar methods.We first described the antibody avidity over time. We reported the avidity of anti-HPV16-VLP antibodies for one-dose and three-dose women by calculating the GMA at each study visit . We also reported the percent change in GMA between two consecutive visits and summarized results for the later years (Years 4–11) by the average percent change per year. We note that all estimates and their CI came from regressing log(avidity) on either an intercept, an indicator for the second study visit, and/or study year, and reporting on the parameter 100 at the time of vaccination. The endpoint was incident, 6-month persistent HPV16 infections, defined as the detection of HPV16 DNA in consecutive cervical samples collected over any 6-month period with no intervening negatives, detected at year 2 or later post-vaccination. Event counting started at year 2 to avoid misclassifying undetected prevalent infections at the time of vaccination as breakthrough infections.6 by evaluating the Pearson correlation coefficient between the log-antibody avidity and log-antibody level among women who were seronegative at first HPV vaccination. To obtain an average correlation over all study years, we normalized all measurements to have a mean = 0 and variance = 1, regressed log-avidity on log-antibody levels using a GEE and reported on β. Third, we evaluated the variability of avidity levels within an individual using “spaghetti” plots and analyses described in the supplementary material. The statistical package used for our analyses is SAS 9.4.For sensitivity analysis, we first repeated the above analyses restricting the percent change results to women with results at both visits being compared. Second, we compared antibody avidity with HPV16 serum antibody levels generated from previous ELISA testing of these samplesFurther information on research design is available in the NPJVACCINES-01464R_Supplemental_Avidity 082521 RESUBMIT_CleanREPORTING SUMMARY


Dalton p16/Ki-67 Dual Stain kit employs the similar immunocytochemical detection and operating procedures with CINtec® PLUS, but its accuracy and efficacy in triaging HPV-positive women need to be evaluated.CINtec® PLUS were subsequently performed, and two DS tests were separately completed in each of the same specimens. The results of two DS tests were head-to-head compared, and their efficacies to identify high-grade cervical intraepithelial neoplasia (CIN) were evaluated, using histopathology of biopsy as the golden standard.A total of 717 HPV-positive specimens of cervical exfoliated cells were included. Cytology, Dalton, and CINtec® PLUS (p < 0.05); both rose with the increased severity of histopathological and cytological abnormalities. Compared to CINtec® PLUS, the positive rate of Dalton was significantly lower in the normal histopathology group (p < 0.05) and lower, but not significantly, in mild abnormal histopathology and cytology NILM and LSIL groups. Two DS tests showed a good consistency , with 100% of consistency in the cytology HSIL group. Inconsistency occurred mainly in the cytology NILM and LSIL groups, with more Dalton negative but CINtec® PLUS positive. Compared to CINtec® PLUS, Dalton showed similar sensitivity (94.59% vs. 91.89%), but significantly higher specificity  and accuracy , with a larger area under the curve (AUC) of 0.849  for identifying CIN3+. The similar results were observed when identifying CIN2+.The overall positive rate of two DS tests were 28.31% for Dalton and 33.89% for CINtec® PLUS, suggesting that Dalton may be superior to CINtec® PLUS and an alternative technique for triaging primary HPV-positive women in cervical cancer screening.Dalton presents the lower false positive rate and better efficacy in identifying high-grade CIN than CINtec Globally, cervical cancer remains the third most common malignancy in women, with approximately 601,000 new cases and 260,000 deaths annually , the AmeCytology is a preferred examination for triaging HPV-positive women because of its high specificity, but it is a subjective judgment, and the accuracy depends on the professional level of the cytologist . There i® PLUS is one of the DS techniques specific to p16 and Ki-67, and its accuracy has been clinically and epidemiologically validated. CINtec® PLUS has also been used as the comparator standard for evaluating various DS tests , were included in this study Figure 1®  or Aptima® HPV Test . HPV testing was performed following the manufacturer’s instructions. The recommended cutoff value is relative light units/cutoff (RLU/CO) ratio ≥1.0 for HC2 assay and signal/cutoff (S/CO) ratio ≥1.0 for Aptima assay. Residual specimens of cervical exfoliated cells after Aptima test were collected for further liquid-based cytology (LBC)  and two DS tests. While in women receiving HC2 test, cervical exfoliated cells were resampled for LBC and two DS tests. All LBC slides were evaluated by at least two pathologists; when inconsistent diagnosis occurred, the slide was read by the third pathologist, and the final diagnosis was made by two of them whose diagnoses were the same. The cytological findings were interpreted and categorized per the 2014 Bethesda System  using Dalton p16/Ki-67 Dual Stain kit  and CINtec® PLUS Cytology kit , respectively. Dalton and CINtec® PLUS DS slides were evaluated by two pathologists who were blind to each other. Positive p16/Ki-67 dual-stained cells were characterized by a brown cytoplasmic/nuclear signal for p16 overexpression and a red nuclear signal for Ki-67 expression within the same cell , negative predictive value (NPV), and accuracy] were summarized using percentages and 95% confidence interval (CI). Likelihood ratio positive (LR+), likelihood ratio negative (LR−), and the receiver operating characteristic (ROC) curve with 95% CI were used to assess the efficacy in detecting high-grade lesions (including CIN3+ and CIN2+). Data were analyzed with software SPSS21.0 and VassarStats (online). All statistical tests were two-sided, and the value of p < 0.05 was considered statistically significant.The chi-square test was used to compare proportions among different groups. Cohen’s kappa was calculated to estimate interobserver consistency between Dalton and CINtecOf the 717 HPV-positive women, 223 (31.10%) received HC2 assay, and other 494 (68.90%) received Aptima assay. For cytology, 331 (46.16%) were abnormal, including 139 (41.99%) of ASC-US , 125 (37.77%) of LSIL , 49 (14.80%) of ASC-H , 13 (3.93%) of HSIL , 3 (0.91%) of SCC (squamous cell carcinoma), 1 (0.30%) of AC (adenocarcinoma), and 1 (0.30%) of AGC-NOS . The remaining 386 specimens were NILM  Figure 1® PLUS test in the same sample, and the representative stains of two DS tests were displayed in ® PLUS, with a significant difference between them (p < 0.05)  and slightly lower in mild abnormal histopathology and cytology NILM and LSIL groups.Dual-stained cytology for p16/Ki-67 was separately performed by Dalton and CINtec < 0.05) Table 1.® PLUS negative, while 77 were Dalton negative but CINtec® PLUS positive, as shown in ® PLUS . Further analysis demonstrated complete consistency between two tests in the cytology HSIL group, and inconsistency mainly occurred in the cytology NILM and LSIL groups, with more Dalton negative but CINtec® PLUS positive, implying that Dalton may possess the potential of lower false positive rate than CINtec® PLUS in identifying high-grade lesions.Totally, 37 specimens were Dalton positive but CINtec® PLUS for predicting high-grade CIN in HPV-positive women (® PLUS (both p < 0.05). Similar results were observed when identifying CIN2+. ROC curves showed that Dalton occupied a larger area under the curve (AUC) in predicting both CIN3+  and CIN2+ . Our results together suggest that Dalton presents the better efficacy than CINtec® PLUS for identifying high-grade CIN in triaging HPV-positive women.The efficacy was further compared between Dalton and CINtecve women Figure 3Dual stain for p16/Ki-67 is a kind of technique using immunohistochemistry specific to p16 and Ki-67, respectively. The p16, a cyclin-dependent kinase inhibitor, acts as a tumor suppressor in most cells , but HPV® PLUS possessed improved performance, compared to cytology, for triaging HPV-positive women  (https://www.fda.gov/media/136682/download) and has been regarded as the comparator standard for evaluating various tests  and accuracy  than CINtec® PLUS, with the equal sensitivity for identifying CIN3+, and the results were similar for identifying CIN2+. Moreover, we observed that Dalton occupied a larger AUC than CINtec® PLUS in identifying both CIN3+ and CIN2+. Our results together suggested that Dalton indeed increased the specificity but did not decrease the sensitivity, compared to CINtec® PLUS, in identifying high-grade CIN. Hence, Dalton may be a superior test to CINtec® PLUS for triaging HPV-positive women.Because of the low specificity of HPV test, a highly specific triage test is very important to reduce colposcopy referral in primary HPV screening. In view of its high specificity, cytology has been recommended as the preferred method for triaging HPV-positive women . Previoucytology , 13, 15.There were still some limitations of our study. All the participants came from a gynecological clinic; the proportions of CIN or above and high-grade CIN or above were 34.73% (249/717) and 11.16% (80/717), respectively, in our series, both appeared to be higher than those in the general population, which implies that there may be bias in our samples. In addition, our cross-sectional study cannot evaluate the long-term risk of high-grade lesions in those Dalton-negative women. Therefore, a longitudinal study on Dalton is needed.® PLUS as triage tests in 717 HPV-positive women and observed a good consistency between the two tests. Inconsistency mainly occurred in normal and mild abnormal cytology with more Dalton negative but CINtec® PLUS positive. Using histopathological diagnosis of the biopsy as the golden standard, Dalton showed better efficacy than CINtec® PLUS with higher specificity and similar sensitivity in identifying high-grade CIN. Our results suggest that Dalton may be superior to CINtec® PLUS in identifying high-grade CIN and is an alternative technique for triaging primary HPV-positive women in cervical cancer screening.In summary, we evaluated Dalton and CINtecThe original contributions presented in the study are included in the article/supplementary material. Further inquiries can be directed to the corresponding author.The studies involving human participants were reviewed and approved by the Ethics Committees of Women’s Hospital, School of Medicine, Zhejiang University. The patients/participants provided their written informed consent to participate in this study.YL, YF, and BC had full access to all the data in the study and took responsibility for the integrity of the data and accuracy of the data analysis. XX and XW designed and organized the study. All authors contributed to the article and approved the submitted version.This study was supported by the Key Research and Development Project of Zhejiang Province (2020C03025).The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


However, herein, we show that p38δ inhibition may be therapeutically beneficial for treatment of specific cancer types, such as skin carcinoma, hepatocellular carcinoma (HCC), head and neck squamous cell carcinoma (HNSCC), cholangiocarcinoma (CC), and breast cancer. This review aims to discuss the roles of p38δ in cancer and summarize the findings of molecules with potential to inhibit p38δ in order to guide the search for new target cancer therapies based on p38δ inhibitors. The p38δ mitogen-activated protein kinase is an important signal transduction enzyme. p38δ has recently emerged as a drug target due to its tissue-specific expression patterns and its critical roles in regulation of cellular processes related to cancer and inflammatory diseases, such as cell proliferation, cell migration, apoptosis, and inflammatory responses. However, potent and specific p38δ inhibitors have not been defined so far. Moreover, in cancer disease, p38δ appears to act as a tumor suppressor or tumor promoter according to cancer and cell type studied. In this review, we outline the current understanding of p38δ roles in each cancer type, to define whether it is possible to delineate new cancer therapies based on small-molecule p38δ inhibitors. We also highlight recent advances made in the design of molecules with potential to inhibit p38 isoforms and discuss structural approaches to guide the search for p38δ inhibitors. Mitogen-activated protein kinase (MAPK) cascades are signaling components that play a key role in transducing extracellular stimuli into cellular responses through phosphorylation of different substrates. MAPK signaling pathways control a variety of cellular processes, such as growth, differentiation, proliferation, survival, and death ,2. The mThe p38 MAPK signaling pathways are activated by a wide variety of environmental and cellular stresses—for example, oxidative stress, hypoxia, and UV irradiation—or by inflammatory cytokines such as tumor necrosis factor (TNF)-α and interleukin (IL)-1β ,5. The uFour members comprise the p38 MAPK family: p38α MAPK14), p38β MAPK11), p38γ (MAPK12 or stress-activated protein kinases 3 - SAPK3), and p38δ (MAPK13 or SAPK4). Based on their amino acid sequence, different expression patterns, and sensitivity to chemical inhibitors, p38 isoforms can be separated into two subgroups: p38α and p38β represent one subgroup with 75% sequence identity, while p38γ and p38δ represent the other subgroup  . In cont, p38β  and tyrosine (Tyr182) residues by the upstream kinases MKK6 or MKK3 ,36. Howe−/− MEFs, but not p38γ−/− and wild-type (WT) MEFs, changed their morphology after reaching confluence and presented impaired contact inhibition. Moreover, either p38δ−/− or p38γ−/− MEFs proliferated faster than WT fibroblasts and displayed increased cell migration and matrix metalloproteinase 2 (MMP2) secretion . Vi. Vi28]. An approach involving targeting protein kinases upstream of p38δ MAPK could be an alternative strategy to achieve specific inhibition of p38δ . The upsp38δ MAPK isoform for a long time was practically forgotten or did not arouse the interest of researchers, mostly because it is not an abundant protein expressed in all tissues as p38α. However, as demonstrated in this review, p38δ has some advantages as a drug target due to its restricted expression pattern. Furthermore, p38δ has several important biological roles, especially in cancer disease where it seems to be a tumor suppressor or promoter, depending on the cancer type. There are several evidences showing that p38δ is responsible for proliferation, migration, and invasion of tumor cells, which is critical for tumor progression and formation of metastasis. Therefore, p38δ inhibition is a potential therapeutic strategy for the treatment of cancer, not only for those in the early stage, but also for advanced stages of the disease. In this context, it is important to take into account that the contrasting roles of p38δ could bring some prejudicial responses when this isoform is inhibited, since it can stop tumor progression in a tissue, while leading to a malignant transformation in others. The selectivity of p38δ inhibitors is important and require special attention, as in some types of cancer the isoforms of p38 (among themselves) may have contrasting roles.Although studies have demonstrated that targeting DFG-out binding mode may have some advantages in p38 inhibition, it has also been shown that p38 inhibitors can bind equally well to both DFG-in and DFG-out mode, with differences in selectivity and potency. Specifically, for p38δ, it looks like inhibitors with a DFG-out binding mode are more potent than those with a DFG-in binding mode. This evidence leads to the conclusion that type-II inhibitors, or maybe type-1½, may be favorable in inhibiting p38δ since they could bind in a DFG-out state. Moreover, the structure of compounds with the proposal to inhibit p38δ needs to consider that this isoform has a bulky methionine as gatekeeper residue, which might impair the binding and selectivity of the inhibitor. Despite the limited success to obtain inhibitors specific to p38δ, this p38 isoform remains a potential candidate for the development of new targeted therapies for cancer. The efforts to design a potent and selective inhibitor of p38δ are important, since the lack of these compounds limits knowledge on p38δ biological functions, as well as delaying the development of new targeted therapies based on p38δ inhibition.


There is a need to increase the vaccine completion rates in women who have already received human papillomavirus (HPV) vaccines. With vaccines requiring multiple doses, designing a vaccination control program and increasing the proportion of women who complete vaccination are critical and remain as huge challenges. Currently, there are no published reports on the differences in the background characteristics between postpartum women who are vaccinated or unvaccinated against HPV. This study aimed to determine the vaccination rates of the second and third doses of HPV vaccination utilizing an achievable HPV vaccination program in postpartum women. In this retrospective study, 243 postpartum women attending Chiayi Chang Gung Memorial Hospital between March and September 2014 were enrolled. These women were classified into two groups: one group received the HPV vaccine under a practical, controlled postpartum HPV vaccination program, and the other group did not. The rates for the second and third rounds of HPV vaccination in postpartum women were calculated. The differences in the background characteristics between the two groups were determined using the Student’s t test, chi-square test or Fisher’s exact test, and the multiple logistic models, as appropriate. Under the controlled postpartum HPV vaccination program, the completion rate for the three doses of postpartum HPV vaccination was 97.2%. Significant differences were observed according to maternal age, gender of the newborn, and postpartum Pap smear results between the two groups in our study. In conclusion, the controlled postpartum HPV vaccination program is a reasonable method for achieving an excellent completion rate for the three doses of postpartum HPV vaccination and may be a good model for any multiple-dose vaccination protocol. Cervical cancer in women is the greatest disease burden caused by the human papillomavirus (HPV) infection . The estCurrently, commercially available HPV vaccines include bivalent HPV vaccine  –15; the According to ACOG data, in the US, although 50% of adolescent girls aged 13-17 years received at least one dose of HPV vaccine, only 33% completed the required three doses . A studyClinical observations have shown that without effective monitoring and management of HPV vaccination, the proportion of women receiving the three doses of HPV vaccine may decrease –28. StudFurthermore, to date, there have been no reports examining the differences in background characteristics between postpartum women who have been vaccinated against HPV and those who have not been vaccinated. In this retrospective study, we provided a practical method and model for the promotion and improvement of the coverage rates of the second and third doses of HPV vaccination. Therefore, this study aimed to determine the vaccination rates of the second and third doses of HPV vaccination utilizing a reasonable HPV vaccination program in postpartum women.Streptococcus (GBS) infection, gestational age, delivery method, single/twins, prenatal testing selection, pregnancy status, delivery complication, and postpartum Pap smear result. The characteristics of the newborn including gender and newborn outcomes were also recorded. This study was approved by the Institutional Review Board (IRB) of the Chang Gung Medical Foundation for clinical trials, and the need for informed consent was waived (IRB No.: 201700098B0).We studied the rationale for postpartum HPV vaccination program in our hospital. In this retrospective study, a total of 243 postpartum women, delivered by a single designated attending physician  from the Department of Obstetrics and Gynecology in Chiayi Chang Gung Memorial Hospital, from March to September 2014 were enrolled. These women were classified into two groups: one group received the HPV vaccine under an achievable, controlled postpartum HPV vaccination program, and the other group did not. The attending physician designed the postpartum HPV vaccination program and performed the delivery for most of the women attending our hospital, including all study subjects. We examined the postpartum HPV vaccination and completion rates for the three doses of HPV vaccines under effective monitoring and determined the differences in background characteristics between vaccinated and unvaccinated women. We also recorded patients’ characteristics such as maternal basic data including age, education level, blood type, occupation, religion, race, parity, postpartum sterilization, Group B The inclusion criteria for this study were as follows: delivery cases by a single designated attending physician from the Department of Obstetrics and Gynecology in Chiayi Chang Gung Memorial Hospital, postpartum women , and live births (with and without newborn complications). To ensure the quality and content of explanations, the designated attending physician , with 10 years of experience in the field of HPV vaccination, who designed the postpartum HPV vaccination program, provided a standard explanation on the benefit, cost, and schedule of postpartum HPV vaccination, as well as vaccine efficacy to the study subjects during the postpartum hospitalization period. The exclusion criteria were the following: non-postpartum women, stillbirths, delivery cases not managed by the designated attending physician, and subjects who were unable to receive the standard explanation of the designated physician in person. Any questions on HPV vaccination asked by the postpartum women were answered. All postpartum women who received HPV vaccine understood the indications for HPV vaccination.Subjects who agreed to undergo vaccination were administered the first dose  during the postpartum hospitalization period. The follow-up visit for postpartum examination was arranged at discharge. The contact phone numbers of included subjects had already been recorded in the outpatient records (mobile phone numbers of both spouses or any telephone number for contact) at the time of the prenatal oral glucose tolerance test (OGTT) at 24-28 weeks of gestation.The second HPV vaccine dose and a reconfirmation of the subject’s contact phone number were carried out at the outpatient postpartum visit. When the date of the third HPV vaccine dose was arranged, the subject was asked to set a reminder on their mobile phones or other devices for the follow-up visit. If patients did not automatically return for a follow-up visit after HPV vaccination, the subjects were contacted for a follow-up visit and an appointment was automatically made. If the subject still did not return for a follow-up visit, a maximum of three repeated attempts was made to contact her. Streptococcus (GBS), gestational age, delivery method , single birth or not, selection of Down screening , pregnancy status , complication , postpartum Pap smear result . The variables of the newborn included gender, neonatal care unit , APGAR score at 1 min/5 min.We collected maternal and newborn related variables from the medical records. The maternal variables included age, education, blood type, occupation, religion, race, parity, abdominal tubal sterilization (ATS), infection with group B P-value <0.05 was considered statistically significant. IBM SPSS for Windows version 22  was used for data analysis.For the statistical analysis, the continuous variables were analyzed using the Student’s t test; the categorical variables were analyzed using the chi-squared test or Fisher’s exact test, as appropriate. Furthermore, we selected the significant related covariates of vaccination willingness in the multivariate analysis. The multiple logistic models were used to determine the effect factors for vaccination willingness. Data were presented as odds ratio (OR) and 95% confidence interval (CI). A two-sided This study included a total of 243 women whose deliveries were assisted by a designated single attending physician from March to September 2014. Overall, 109 (44.9%) women were administered postpartum HPV vaccination and 134 (55.1%) were not. During the study period, the postpartum HPV vaccination program Figure 1P=0.02). There were significant differences in educational levels of the women between the two groups (P=0.02). The proportion of women with university-level education and above was higher in the vaccinated group than in the unvaccinated group, whereas the proportion of women with below university-level education was higher in the unvaccinated group than in the vaccinated group.We further examined the background characteristics of differences between vaccinated and unvaccinated subjects Table 1.P=0.03). A higher proportion of vaccinated subjects were medical staff or civil servants, while a higher proportion of unvaccinated subjects were in the service industry, laborers, or unemployed. There were significant differences in postpartum Pap smear results between the vaccinated and unvaccinated groups (P=0.006). Of the 109 subjects in the vaccinated group 72,5% (N=79), 22.9% (N=25), and 4.6% (N=5) had normal or abnormal results, or did not undergo Pap smears, respectively. All subjects in the vaccinated group with abnormal Pap smear results completed the three doses of HPV vaccine. Among the three subjects who did not complete three doses of HPV vaccines, all had normal postpartum Pap smear results. There were significant differences in the gender of the newborn (P=0.03).There were significant differences in occupation between the vaccinated and unvaccinated groups (P=0.84), religion (P=0.51), race (P=1.00), primipara/multipara, postpartum sterilization, and infection with group B Streptococcus during pregnancy between the two groups . No significant differences were observed in post-term deliveries (≥42 0/7 weeks), full-term deliveries (37 0/7-41 6/7 weeks), mild preterm deliveries (34 0/7-36 6/7 weeks), and severe preterm deliveries (≤33 6/7) between the two groups (P=0.92); gestational periods ≥37 0/7 and <37 0/7 (P=0.75); delivery method and delivery of single/twin births . There were no significant differences between the vaccinated and unvaccinated groups in selection of prenatal Down syndrome screening (P=0.25). Further comparisons between NIPT and quadruple test, and between amniocentesis with non-invasive Down syndrome screening  also showed no statistical differences . There were no significant differences between the vaccinated and unvaccinated groups in terms of normal/high-risk pregnancies or in complications during delivery .There were no significant differences in maternal blood type (P=0.41), in Appearance, Pulse, Grimace, Activity, and Respiration (APGAR) score (≥7 and <7 points) in the first and fifth minute (P=0.50).In neonatal outcomes, there were no significant differences between the vaccinated and unvaccinated groups in neonatal care unit  when compared to those who received the more expensive NIPT,  (P=0.18), suggesting that the choice of Down syndrome screening does not play a major role in their acceptance of postpartum HPV vaccination.It was especially surprising to find no difference between groups with respect to infection with Group B  section Table 1.P=0.25 and 0.21, respectively) (in P=0.02)  as well as HPV infection status according to the database of our postpartum HPV vaccination program, to evaluate the efficacy of postpartum HPV vaccination.The original contributions presented in the study are included in the article/supplementary material. Further inquiries can be directed to the corresponding author.Written informed consent was obtained from the individual(s) for the publication of any potentially identifiable images or data included in this article.C-YL designed the study. C-YL conducted the systematic review and analyzed the data with help from C-CC. C-YL wrote the manuscript, and then C-JT, M-CL, and S-FY critically revised it before all authors read and approved the final version. All authors contributed to the article and approved the submitted version.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Introduction of human papillomavirus (HPV) vaccination has been slow in low-income and middle-income countries (LMICs) because of resource constraints and worldwide shortage of vaccine supplies. To help inform WHO recommendations, we modelled various HPV vaccination strategies to examine the optimal use of limited vaccine supplies and best allocation of scarce resources in LMICs in the context of the WHO global call to eliminate cervical cancer as a public health problem.In this mathematical modelling analysis, we developed HPV-ADVISE LMIC, a transmission-dynamic model of HPV infection and diseases calibrated to four LMICs: India, Vietnam, Uganda, and Nigeria. For different vaccination strategies that encompassed use of a nine-valent vaccine , we estimated three outcomes: reduction in the age-standardised rate of cervical cancer, number of doses needed to prevent one case of cervical cancer , and the incremental cost-effectiveness ratio . We examined different vaccination strategies by varying the ages of routine HPV vaccination and number of age cohorts vaccinated, the population targeted, and the number of doses used. In our base case, we assumed 100% lifetime protection against HPV-16, HPV-18, HPV-31, HPV-33, HPV-45, HPV-52, and HPV-58; vaccination coverage of 80%; and a time horizon of 100 years. For the cost-effectiveness analysis, we used a 3% discount rate. Elimination of cervical cancer was defined as an age-standardised incidence of less than four cases per 100 000 woman-years.We predicted that HPV vaccination could lead to cervical cancer elimination in Vietnam, India, and Nigeria, but not in Uganda. Compared with no vaccination, strategies that involved vaccinating girls aged 9–14 years with two doses were predicted to be the most efficient and cost-effective in all four LMICs. NNV ranged from 78 to 381 and ICER ranged from $28 per DALY averted to $1406 per DALY averted depending on the country. The most efficient and cost-effective strategies were routine vaccination of girls aged 14 years, with or without a later switch to routine vaccination of girls aged 9 years, and routine vaccination of girls aged 9 years with a 5-year extended interval between doses and a catch-up programme at age 14 years. Vaccinating boys (aged 9–14 years) or women aged 18 years or older resulted in substantially higher NNVs and ICERs.We identified two strategies that could maximise efforts to prevent cervical cancer in LMICs given constraints on vaccine supplies and costs and that would allow a maximum of LMICs to introduce HPV vaccination.World Health Organization, Canadian Institute of Health Research, Fonds de recherche du Québec–Santé, Compute Canada, PATH, and The Bill & Melinda Gates Foundation.For the French and Spanish translations of the abstract see Supplementary Materials section. Globally, in 2020, an estimated 604 000 new cases of cervical cancer and 342 000 cervical cancer-related deaths occurred.Evidence before this studyApproximately 500 000 new cases of cervical cancer are diagnosed in low-income and middle-income countries (LMICs) each year. Human papillomavirus (HPV) vaccines are highly effective: the Papillomavirus Rapid Interface for Modelling and Economics (PRIME) model predicted that HPV vaccination of girls aged 12 years with two doses of the vaccine was cost-effective in 156 (87%) of 179 countries. However, less than 40% of LMICs have introduced HPV vaccination programmes. Key barriers to introduction include financial and human resource constraints, and, since 2019, a worldwide shortage of HPV vaccine supply that might last until 2024. These barriers might have been intensified by the COVID-19 pandemic. In parallel, the WHO director-general has issued a global call to eliminate cervical cancer as a public health problem, which will result in sustained efforts to achieve high vaccination coverage across LMICs.Added value of this studyIn this modelling analysis we identified two novel HPV vaccination strategies that should minimise the number of doses needed to prevent one case of cervical cancer and the cost per DALY averted: two-dose routine vaccination of girls aged 14 years with or without a later switch to routine vaccination of girls aged 9 years, and routine vaccination of girls aged 9 years with an extended interval of 5 years between doses and a catch-up programme for girls aged 14 years. These strategies would maximise prevention of cervical cancer with the fewest doses in the short term and at the lowest cost, which would allow a maximum of LMICs to introduce HPV vaccination and could reduce the effect of HPV vaccine supply shortage on efforts to eliminate cervical cancer.Implication of all the available evidenceOur modelling results have directly informed WHO Strategic Advisory Group of Experts on Immunization's recommendation in October, 2019, to continue vaccination with a two-dose schedule; temporarily postpone vaccination of multiple-age cohorts, older age groups (≥15 years), and gender-neutral vaccination; and consider implementing strategies such as those identified in our study.Because of the substantial burden and inequalities in the distribution of cervical cancer across the world, the WHO Director-General Tedros Adhanom Ghebreyesus made a global call for action towards the elimination of cervical cancer as a public health problem.The main HPV vaccination policy questions being examined in LMICs by their health authorities and by WHO are as follows: what are the ages and the number of age cohorts that should be vaccinated? Should only girls or girls and boys be vaccinated? And how many and when should doses be given per vaccinee?In this Article, we present the modelling results that were presented to the WHO Strategic Advisory Group of Experts on Immunization (SAGE) in October, 2019, to help inform their global HPV vaccination policy recommendations.Demographic Health Survey data, the mean number of lifetime sexual partners for men was 1·4 in Vietnam, 1·9 in India, 4·1 in Nigeria, and 6·6 in Uganda; the estimated HPV prevalence in a 2010 meta-analaysisonline).In this mathematical modelling analysis, we modelled the impact of HPV vaccination in four countries: India, Vietnam, Uganda, and Nigeria. We selected these countries because of differences between their populations in sexual behaviour, HPV prevalence, and cervical cancer burden. For example, according to For the four countries, we first compared seven HPV vaccination scenarios with two doses, starting with routine vaccination of girls aged 9 years. We then added the vaccination of multiple-aged cohorts of girls and women aged 9–14 years, 9–18 years, or 9–25 years within the first year of the programme. Finally, we added the vaccination of boys aged 9–14 years to the previous multiple-aged cohort vaccination scenarios of girls and women . BecauseTo examine HPV vaccination policy questions in LMIC settings we developed HPV-ADVISE LMIC, an individual-based, transmission-dynamic model of multiple types of HPV infection and disease . HPV-ADVIn HPV-ADVISE LMIC, individuals are attributed one of four mutually exclusive levels of sexual activity: level 0, including women and men who are married and remain married to a single partner throughout their life; level 1, including women who get married and then divorce or whose partner has a concurrent partner during their marriage  and men who get married and then divorce or have a concurrent partnership during their marriage ; level 2, including women and men who never get married; and level 3, including female sex workers and men who pay for sex. Notably, men who pay for sex can also have concurrent long-term partnerships with level 0–1 women. These definitions of levels of sexual activity were chosen because they are good markers of sexual behaviour and risk of HPV infection in these countries, and valid data sources are available . The modWe parametrised and calibrated the model to each country separately. We estimated the parameter values determining sexual behaviour, HPV transmission, and the natural history of HPV infection and cervical cancer by calibrating the model to country-specific data . For eacWe obtained age-specific and country-specific mortality rates from the WHO Global Health Observatory data repository25We assumed that the HPV vaccines were prophylactic and do not affect the natural history of HPV infection or disease among individuals infected by a vaccine type before vaccination. In the model, vaccine efficacy is specific to each of the 18 HPV types modelled. In our base case, we assumed that two doses of HPV vaccine provide 100% efficacy against infection with HPV-16, HPV-18, HPV-31, HPV-33, HPV-45, HPV-52, and HPV-58  and that duration of protection is lifelong. In sensitivity analyses, we investigated one-dose vaccination strategies, in which we assumed that one dose of vaccine could provide an efficacy against infection of 95% or 85% with a duration of protection of 30 or 20 years. We also varied vaccine efficacy against cross-protective types for the two-valent and four-valent vaccines  and $7·50 per dose (1·5 × Gavi price) in 2017 international $ (INT$). The vaccine delivery and operational costs were country specific and based on estimates from the Papillomavirus Rapid Interface for Modelling and Economics (PRIME) model.We had three main outcomes . First, For age-standardisation of the incidence of cervical cancer, we used the age structure of the 2015 world female population aged 0–99 years.We modelled a 100-year time-horizon to capture both short-term and long-term benefits of HPV vaccination on the incidence of cervical cancer and associated mortality .We present all model predictions with the 10th and 90th percentiles  of the model predictions taken from the distribution of 1000 simulation results for each country (50 parameter sets × 20 simulations per parameter set), and the mean of the ten parameter sets that provide the best fit (using weighted least squares) to the estimated incidence of cervical cancer from Globocan 2020.WHO contributed to the study design, data collection, data analysis, data interpretation, and writing of the report. The Canadian Institute of Health Research, Fonds de recherche du Québec - Santé, The Bill & Melinda Gates Foundation, and Compute Canada had no role in the study design, data collection, data analysis, data interpretation, or writing of the report.All described analyses model vaccination with two doses of HPV vaccine, unless otherwise indicated. Under base case assumptions, we predicted that routine vaccination of girls only, with 80% coverage, would lead to substantial decreases in the incidence of cervical cancer . At equiOur model predicts that routine vaccination of girls aged 9 years, with vaccination of girls aged 9–14 years in the first year of the programme as part of a multiple-aged cohort vaccination programme combines the advantages of the long-term benefit of routine vaccination of girls aged 9 years and the faster decreases in incidence that were seen with routine vaccination of girls aged 14 years . VaccinaOur model predicts very similar population-level effectiveness with the different vaccination strategies of girls aged 9–14 years . The posvs 50–87% with girls-only vaccination with multiple-aged cohort vaccination of girls aged 9–14 years; Vaccinating boys in addition to girls with two doses of vaccine both accelerates the decrease in age-standardised incidence of cervical cancer and further decreases the incidence at equilibrium . In the Our model predicted that, compared with no vaccination, routine vaccination of girls aged 9 years, with additional vaccination of girls aged 9–14 years in the first year of the programme, was the most efficient and cost-effective vaccination strategy in all four countries, when varying simultaneously the number of cohorts, age of cohorts, and population targeted for vaccination. This strategy extendedly dominated routine vaccination of girls aged 9 years only  in countries with incidences of cervical cancer between those of Vietnam  and Nigeria (34 cases per 100 000 woman-years), but not in countries with an incidence similar to, or higher than, that of Uganda (57 cases per 100 000 woman-years), despite such countries potentially achieving substantial reductions in the incidence of cervical cancer. In countries like Uganda, adding cervical screening to female or gender-neutral vaccination will likely be required to reach elimination. Indeed, one modelling study suggested that the addition of twice lifetime HPV screening at ages 35 years and 45 years to HPV vaccination is needed for elimination of cervical cancer in countries with high incidences.35Our findings have important implications for HPV vaccination policy decisions in LMICs in the context of limited supplies of vaccine. Our results suggest that the most efficient HPV vaccination strategies, as measured by NNV, are those that target girls aged 9–14 years. By contrast, vaccinating older girls and women or boys is much less efficient, with NNVs that are up to ten times higher than when vaccinating girls aged 9–14 years. Partly based on these results, in October, 2019, SAGE recommended that countries should temporarily postpone the implementation of gender-neutral vaccination and vaccination of girls and women in older age groups (≥15 years), at least until HPV vaccine supply shortages are resolved.vs routine vaccination of girls aged 9 years or multiple-age cohort vaccination of girls aged 9–14 years) will depend on the proportion of girls who are sexually active before the age of vaccination and whether sufficiently high vaccination coverage can be achieved. We found that the long-term population-level effectiveness of routine vaccination of girls aged 14 years would be 3–4% percentage points lower than routine vaccination of girls aged 9 years in countries such as Nigeria and India, which have a relatively high proportion of girls aged 14 years who are sexually active (15–25%).Our results suggest that routine vaccination of girls aged 13 or 14 years, with or without a later switch to routine vaccination at an earlier age , would allow countries to retain the accelerated impact of vaccinating multiple-age cohorts while restricting the number of doses required in the first years after programme implementation. Compared with routine vaccination of girls aged 9 years, routine vaccination of girls aged 14 years has two main advantages: it accelerates health benefits by targeting girls closer to becoming sexually active, and it targets girls just before they age out of the 9–14 years age category (these girls would be missed with routine vaccination at younger ages). However, the population-level effectiveness of routine vaccination of girls aged 13 or 14 years  or type of vaccine . Finally, we developed these vaccination strategies for girls aged 9–14 years in collaboration with the WHO HPV Working group to ensure that our modelling results were responsive to the needs of policy makers.Our study has five major strengths. First, to our knowledge, this is the first comprehensive modelling analysis to simultaneously compare HPV vaccination strategies with different ages at vaccination, numbers of age cohorts targeted, gender targeted, numbers of doses, and intervals between doses. Second, our model was calibrated to LMIC-specific sexual activity and epidemiological data. We selected two Asian and two African countries, representing different profiles in terms of sexual activity and HPV-related burden, for which good-quality data were available for us to calibrate and validate our model. Even though these countries are very different in terms of number of lifetime partners and incidence of cervical cancer, the optimal HPV vaccination strategies in terms of efficiency and cost-effectiveness were consistent. Hence, our results are probably generalisable to most LMICs, except potentially LMICs in the Middle East and north Africa, which have a lower incidence of cervical cancer than other LMICs. Third, our model predictions are based on 50 parameter sets, capturing uncertainty in key parameters and within-country variability in sexual activity and HPV and cervical cancer epidemiology. Fourth, our model predictions, which suggested that all vaccination strategies for girls aged 9–14 years we investigated are highly efficient and cost-effective, are robust when using a different number of doses  and long-term routine vaccination at a younger age (to maximise coverage and minimise the likelihood of vaccinating previously infected girls). Second, our model does not account for the effect of HIV, which increases the likelihood of acquisition of HPV and disease progression, or the effect of HIV treatment, which might attenuate the effects of HIV on HPV acquisition and disease progression. Hence, the effect of HPV vaccination on the incidence of cervical cancer might be overestimated in settings with a high prevalence of HIV or might mean that specific prevention strategies might be required for people living with HIV to enable elimination of cervical cancer. These questions are being examined as part of the WHO Cervical Cancer Elimination Modeling Consortium.In summary, HPV vaccination strategies that target girls aged 9–14 years are the most optimal for use of scarce resources. In the context of limited supply of HPV vaccines and the COVID-19 pandemic, two-dose routine vaccination of girls aged 13 or 14 years, with or without a later switch to routine vaccination at an earlier age and routine vaccination at age 9 or 10 years with an extended interval of 3–5 years between doses combined with a programme of catch-up vaccination of girls aged 14 years are the strategies that would minimise the number of doses required in the short term for maximum prevention of cervical cancer. These strategies would allow the maximum number of countries to introduce HPV vaccination and could reduce the effect of vaccine supply shortage on efforts to eliminate cervical cancer.No individual participant-level data were used in this study. Descriptions of the model structure, the parameters included in the model, and the empirical data used for calibration and validation are available in appendix 3.We declare no competing interests.


OR = 1.5; 95% CI: 1.08–1.98); being eldest son , being mother , parents with high educational level  and their knowledge of HPV and HPV vaccine . Average WTP value for full doses of HPV vaccine was 137.5 USD, ranging between 9 USD and 188.3 USD. Parents' knowledge of HPV and HPV vaccine was the only factor affecting WTP value . The findings suggest a strategy be introduced for HPV vaccination to male adolescents in Vietnam.Human papilloma virus (HPV) vaccine for adolescents was recommended as an effective prevention strategy of HPV-related cancers. In Vietnam, HPV vaccination has not been introduced to male adolescent. This study was conducted to examine the acceptance of having boys vaccinated against HPV and its underlying reasoning, and to identify their parent's willingness to pay (WTP) for HPV vaccination in central Vietnam. 785 parents of boys were directly interviewed based on a structured questionnaire. Parent's acceptability of HPV vaccine for their sons was identified by one question with response on 3-point scale . Multivariate logistic regression model was used to determine contributing factors to participant's acceptance. Bidding game method was applied to elicit WTP values for HPV vaccination with initial bid of 161.2 USD. The results showed that 49.2% of parents agreed to have their sons vaccinated against HPV. Factors that influenced parent's acceptance including son's age older than 12 years ( Human papilloma virus (HPV) is a common group of viruses that are mainly transmitted through sexual contact. Globally, HPV infection has been considered as one of the most common viral infections with an estimation of 32.1% HPV-positive women in 2011. In men, the global prevalence rate of genital HPV infection is almost similar to that in women (2–44%). The prevalence of HPV infection is higher in developing countries and young people  . The CenAccording to WHO, 100 countries introduced HPV vaccine into their national vaccination program by 2019; however, they have focused on girls and young women as target population . MedicalIn Vietnam, the prevalence of HPV infection among women varied across population ranging between 2 and 11% . InformaA cross-sectional study was conducted at secondary schools in Hue city which is the capital of Thua Thien Hue province located in central Vietnam. The city has 27 wards which are administrative divisions of the city. These wards are divided into two regions, north and south of Huong river. In 2020, the city has 24 secondary schools with 19,600 students. In Vietnam, secondary schools include 4 grades from sixth to ninth grade, which usually involve students ages 11–15.The study randomly selected four schools as representatives of geographical regions of the city. Two schools are among 13 schools on the north and others are among 11 schools on the south of the river; then at each region, one school in the central city and another in its periphery were also randomly chosen on the basis of their location on the map of the city. Participants, who were parents of male students and agreed to enroll in the study, were invited to interview. In each school, we conducted interviews after class with the support of homeroom teachers. A total of 785 parents completed the interview giving a response rate of 92.6%.Data were collected in December 2020 when all schools organized a parent meeting at the beginning of a new school year. After the meeting finished, parents were interviewed directly at the classroom using a structured questionnaire. The interviewers, who were staff and graduated students of the Faculty of Public Health in University of Medicine and Pharmacy, Hue University, were trained on the content of the questionnaire and skills of interview.The questionnaire consisted of three parts: part 1 was personal characteristics of participants and their sons, family history of HPV-related diseases and HPV vaccination of sons; part 2 was questions to assess parent's knowledge of HPV infection and HPV vaccine; and part 3 was about parent's acceptance and the price of WTP for HPV vaccination for their sons. The questionnaire was pre-tested on 20 random parents of boys ages 11–15 in Hue city and revised before implementing data collection. These parents were not selected from study settings.The knowledge about HPV infection and HPV vaccine was measured by 14 statements , with the convention that 1 point for a correct answer and 0 point for wrong or “don't know” answer. The maximum possible total score for knowledge was 14. The knowledge was rated as “good” for total score of 7 and above; total scores below 7 were characterized as “not good.” The questions about knowledge of HPV infection and its vaccine were developed on the basis of document on HPV of CDC . The relParent's acceptability of HPV vaccine for their sons was identified by one question “do you agree to vaccinate against HPV for your son?” with response on 3-point scale . Parents who chose the answer “agree” were continued to be interviewed to obtain a maximum price that they were willing to pay for full doses of HPV vaccine for their son. The bidding game method of contingent valuation was used to elicit WTP price for two doses of Gardasil vaccine. In this study, the initial bid was 3,580,000 VND (about 161.2 USD) that was the current market price for two doses of Gardasil at the time of the survey. The parents would be asked “are you willing to have your son vaccinated against HPV with a price of 3,580,000 VND?” If the answer was “yes,” the next questions would increase price incrementally by 200,000 VND (9 USD) until the answer was “no.” Then maximum WTP was final price that received the answer “yes.” If their answer was “no,” the next questions would decrease price incrementally by 200,000 VND until the answer was “yes,” and that was maximum WTP. These incremental levels were on the basis of pre-survey on 20 parents of boys ages 11–15 in Hue city. In the study, the lowest price was suggested to be 2,980,000 VND (134.2 USD); however, parents could choose any price in case they could not accept that lowest price. WTP price was presented in both VND and USD. The exchange rate used was that in effect on December 15, 2020 .SD, median, and min–max. However, data of WTP was not a normal distribution; non-parametric tests  and spearman correlations were used to reveal factors affecting WTP price. An alpha value of 0.05 was considered statistically significant.Descriptive statistics including frequency and percentage was used to summarize the personal characteristics of parents and their sons and the acceptability of HPV vaccination for sons. Multivariate logistic regression model was employed to identify the determinants of parent's acceptability of HPV vaccination for their sons. WTP for HPV vaccination was presented by mean, SD = 6.1) ranging between 29 and 62. Their educational levels were rather high with 44.8% of them attaining college degree or higher. More than half of the parents had unstable income. Twenty-one participants (2.7%) had no income; they were either unemployed or housewife. Most of the participants were maintaining marital status (94.6%). There were 24 parents (3.1%) whose households were classified as poor or near poor. Almost all of them (98.1%) reported that no one of their family suffered a HPV-related disease. The number of children of each parent ranged from 1 to 7  and their average number of sons were 1.5 (SD = 0.6) ranging between 1 and 5. Majority of the parents indicated that both father and mother were responsible for making decision on their children's health. The number of male students whose parents participated in the study was distributed higher into sixth and seventh grades. Their mean age was 12.4 years (SD = 1.2) ranging between 11 and 15. More than half of the boys were the eldest son. There were 22 sons (2.8%) who suffered either a chronic disease or a birth defect. None of boys was vaccinated against HPV before.The knowledge about HPV and HPV vaccine of parents was described in The study showed that 49.2% of the parents agreed to have their son vaccinated against HPV vaccine.OR = 1.5; 95% CI: 1.08–1.98) and 1.6 times  to accept HPV vaccination for their sons more than their counterparts, respectively. The mothers were 1.4 times more likely than the fathers to agree to have their son HPV vaccinated . The parents with good knowledge of HPV infection and HPV vaccine were more likely to accept HPV vaccine compared to those with worse knowledge . The parents who attained college degree or higher were more likely to get HPV vaccine for their sons than those with a lower level of education .Results from multivariate logistic regression analysis revealed factors affecting parents' intention to have their sons vaccinated . Parentsp-values > 0.05)  .On average, WTP amount for two doses of HPV vaccine was 3,053,005 VND (about 137.5 USD) ranging from 200,000 VND (9 USD) to 4,180,000 VND (188.3 USD). Among the parents who accepted to get their sons vaccinated, 63.7% of them were willing to pay <3,580,000 VND (161.2 USD) for two doses of Gardasil .p > 0.05) ( > 0.05) .One noticeable finding is that no participant reported prior HPV vaccination for their sons . In lineAlthough the level of awareness of HPV and HPV vaccine was low among parents in the study, nearly half of them agreed to have their sons vaccinated against HPV in the future. The results from the multivariate analyses indicated that the strongest factor for accepting HPV vaccination was knowledge of HPV and HPV vaccine among the parents.This finding is consistent with many previous studies in Vietnam as well as in other countries , 25, 31.The present study showed that there was a demand to get the sons vaccinated against HPV among their parents. Average WTP price was 137.5 USD for full doses of HPV vaccine, accounting for 6% of annual income per capita in 2020 in Vietnam . This vaThe knowledge of parents about HPV and its vaccine were the only factor affecting WTP price from the study; however, this correlation was weak. A better awareness of HPV and HPV vaccine by the participants raised their WTP price for HPV vaccination. Similarly, studies found that individuals who recognized high risk of COVID-19 tended to pay more for vaccine than those who saw it as low risk , 48. CerThe study has some limitations. First, this is a school-based survey; the sample was randomly selected but based on a list of parents who were present at the parent meeting of the school. Selection bias could be a potential problem. Second, the study was conducted in Hue city where many of traditional family values remained unchanged. In addition, income per capita in study setting was much lower than that in big cities of Vietnam. These can limit ability to generalize findings of the study. Third, the incremental level by 200,000 VND that resulted from a pilot survey could limit choice of respondents. Despite these limitations, this is the first study in Vietnam to identify the demand of HPV vaccine for male adolescents among their parents. The results can support health policy makers to introduce HPV vaccination for males in the country.There was a demand for HPV vaccination for male adolescents among our sampled parents; however, their WTP price for the current vaccine was lower than its market price. Public awareness of HPV and HPV vaccine for both sexes need to be strengthened and sustained. The vaccine against HPV should be introduced to male adolescents besides girls and young women in Vietnam. Government's subsidies should be considered to encourage HPV vaccination for both sexes in the country. This will contribute to reduce not only HPV-related diseases in men, but also the risk of cervical cancer in women.The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.The study proposal was approved by the Ethics Committee for Biomedical Research of University of Medicine & Pharmacy, Hue University . In addition, approval for data collection at the sites was obtained by directors of secondary schools. The interview of study subjects was performed with their verbal permission after they were given adequate information about the study.LN: conception, design of the study, data analysis, and writing the manuscript. TL and NL: data collection, data entering, and data analysis. NT: data collection. All authors have read and agreed to the published version of the manuscript.The research was supported by the research funds from Hue University (DHH 2020- 04- 113).The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.