Background: We aimed to estimate the incidence of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) seroconversion after baseline screening among oncology healthcare workers (HCW). Methods: This is a prospective longitudinal cohort study of HCW, applied at Centro de Terapia Oncológica (CTO), an Oncology clinic in Petrópolis, Brazil. Baseline screening for SARS-CoV-2 occurred between April 9 -29, 2020 using rapid IgM and IgG serological tests for all HCW. Follow-up serology testing took place once between November 5-December 28, 2020 and included retesting with indirect chemiluminescence immunoassay LIAISON SARS-CoV-2 S1/S2 IgG all HCW for seroconversion incidence. Reverse transcriptase–polymerase chain reaction (RT-PCR) testing was offered at baseline and follow-up for all symptomatic staff. The McNemar test was used to assess the change in positive serology incidence in both tests. Results: The study included 60 HCW, with 40 females (66.7%). Mean age was of 43.4 years old (SD =14.5). At baseline SARS-CoV-2 antibody assessment, 57 (95%) were negative and 3 (5%) positive;59 (98%) asymptomatic HCW, and 1 symptomatic (1.6%) tested positive in RT-PCR. A total of 11 RT-PCR were performed since baseline until follow-up in symptomatic HCW, with 9 (81.8%) positive results, all of them with seroconversion. 6 (10%) asymptomatic HCW were seropositive at follow-up screening. None of baseline positive-serology asymptomatic HCW sustained their serology. Seroconversion occurred in 15 (25%) HCW - Table. The incidence of positive serologies in follow-up screening was statistically higher than at baseline (p = 0.008). [Formula presented] Conclusions: Most seroconversions were in symptomatic HCW, although the substantial number of positive serologies in asymptomatic HCW accent the importance and direct impact of regular universal testing. Seropositivity increased five-fold compared to baseline results. This detected increase in infections reflects a national pattern, suggesting community-based and not nosocomial transmission. Legal entity responsible for the study: The authors. Funding: Has not received any funding. Disclosure: All authors have declared no conflicts of interest.
1603P SARS-CoV-2 seroconversion among oncology healthcare workers in Brazil