Association entre la vaccination contre le Virus du Papillome Humain (VPH) et la prévalence de l’infection à VPH dans une cohorte de femmes enceintes de 2010 à 2016 à Montréal
Background: HPV Immunization programs have been implanted in numerous countries worldwide. In Canada, in 2007-2008, many provinces including Quebec, had implemented school-based vaccination programs using 4vHPV vaccines (Gardasil®). While HPV vaccination efficacy has been demonstrated in clinical trials, it is important to verify vaccine effectiveness (VE).  Objective: To estimate VE and herd immunity of the 4vHPV vaccine using HPV prevalence data within a cohort of Canadian pregnant women.  Methods: Baseline data was gathered from a cohort of pregnant women (HERITAGE study) recruited in Montreal between 2010-2012 and 2015-2016. Cervicovaginal samples were collected in the first trimester of pregnancy and tested for HPV DNA of 36 mucosal genotypes. Vaccination status was self-reported in a questionnaire. VE and 95% confident intervals (CI) were estimated by comparing the prevalence of HPV between vaccinated and unvaccinated women using the 1 – odd ratio (OR) formula. Herd immunity was also studied by comparing HPV prevalence in unvaccinated women between the 2 recruitment periods. For both objectives, the OR (and 95% CI) adjusted for age and number of sexual partners in the last 12 months was estimated using exact logistic regression. Results: The proportion of vaccinated women was 7.06% with an average age of vaccination of 25.1 years (SD +/- 5.9).VE for HPV infections 6, 11, 16, and 18 was found to be 69.6% (95% CI: -24.4 – 96.5%). VE for HPV-31, 33, and 45 was 45.1% (95% CI: -93.5 – 99.0%). We also observed a non-statistically significant reduction in the prevalence of HPV-6, 11, 16 and 18 and HPV-31, 33 and 45 unvaccinated women who were recruited during the second recruitment period (2015-2016) compared to those recruited during the first recruitment period (2010-2012) with adjusted OR of 0.9 (95% CI: 0.4-2.0) and 0.7 (95% CI: 0.3-1.6), respectively. Conclusions: We observed a reduction of the prevalence of HPV-6, 11, 16 and 18 and HPV-31, 33 and 45 in vaccinated women. Although these reductions are not statistically significant, they are similar to those observed in other studies.
Virus Papillome humain (VPH) Vaccination HPV Gardasil Human Papillomavirus (HPV) Prevalence HPV vaccination Vaccine effectiveness Herd immunity Cross-protection