SARS-CoV-2 Antibody Prevalence Among 85,529 Healthcare Workers Following the First Wave of COVID-19 in Chile

Abstract

Background: Healthcare workers (HCWs) are at increased risk for SARS-CoV-2 infection, however not all face the same risk. We aimed to determine antibody prevalence and risk factors associated with seropositivity in the Chilean HCW community. \n \nMethods: This was a nationwide, cross-sectional study consisting of a questionnaire and COVID-19 antibody testing. All HCWs in the Chilean public health care system were invited to participate three to four months following the peak of the country s first wave. \n \nFindings: Overall SARS-Cov-2 blood antibody positivity by fingerstick or venipuncture in 85 529 HCWs was 7 · 2%, ranging from 1 · 6% to 12 · 4% between regions. SARS-Cov-2 positive PCR results were self-reported in 8 330 individuals (9 · 7%) of which 47% were seropositive. Overall 10 863 (12 · 7%) either reported prior PCR positive results and/or were seropositive. Several factors were independently associated with higher IRR for seropositivity, including working in hospital (IRR 1·484), medicine/surgery w ards (IRR 1·383), emergency room (IRR 1·266), and night shifts (IRR 1·616), as were\xa0 history of contact with a confirmed case (IRR 1·462), and use of public transport (IRR 1·367). These variables remained significant when including self-reported PCR positive cases in the model. \n \nInterpretation: HCWs in the hospital were at highest risk for COVID-19, especially if working in medicine/surgery wards or emergency rooms, in night shifts, older age, exposed to confirmed cases and/or using public transport. Antibody results using lateral flow likely underestimated true infection rates by nearly 40-50%. Nevertheless, risk factors were sustained when adjusting for self-reported PCR positive cases. \n \nFunding: No funding institution. \n \nConflict of Interest: Authors do not declare any conflict of interest. \n \nEthical Approval: The study was designed in August 2020 by Health Ministry personnel in conjunction with an academicadvisory board; the study was approved by the Ethical Committee of the Servicio de Salud Araucania Sur (No CEC-201, August 10, 2021).