The seroprevalence of SARS-CoV-2 antibodies among health care workers before the era of vaccination: a systematic review and meta-analysis

Background: The prevalence of SARS-CoV-2 infection among health care workers (HCWs) provides information about the spread of COVID-19 within health care facilities, and the risk groups. Objectives: We aimed to describe the rate of SARS-CoV-2 seroprevalence and its determinants among HCWs. Data sources: We used Web of Science, PubMed, Scopus, MEDLINE, EBSCOhost and Cochrane Library. Study eligibility criteria: We included the reports of SARS-CoV-2 seroprevalence with a sample size of minimum 1000 HCWs. Methods: The study was registered at the International Prospective Register of Systematic Reviews (PROSPERO, no. CRD42021230456). We used PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. The keywords were COVID-19, SARS-CoV-2, Coronavirus, seroprevalence, health care workers and risk factors. Results: In total 4329 reports were retrieved, duplications were removed; after filtering according to the title and abstract, 25 studies were selected. Risk of bias was assessed in 25 studies; it was low in 13 studies, medium in four studies, and high in eight studies. In meta-analysis using the random effect model, the weighted average of seroprevalence was calculated as 8% (95% CI 6-10%). The pooled seroprevalence rates of the selected variables that have a rate above the average were male HCWs with 9% (95% CI 7-11%); HCWs from ethnic minorities with 13% (95% CI 9-17%); high exposure 9% (95% CI 6-13%); exposure to the virus outside the health care setting 22% (95% CI 14-32%). Conclusions: Our analysis indicates a SARS-CoV-2 seroprevalence rate of 8% among studies that included >1000 HCWs for the year 2020, before vaccinations started. The most common risk factors associated with higher seroprevalence rate were ethnicity, male gender and having a higher number of household contacts. Working as a frontline HCW was inconsistent in its association with higher seroprevalence. _Ilker Kayi, Clin Microbiol Infect 2021;27:1242 (c) 2021 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Automated summary

The study found a SARS-CoV-2 seroprevalence rate of 8% among HCWs in 2020, before vaccinations started, with higher rates observed in male HCWs, HCWs from ethnic minorities, those with high exposure, and those exposed to the virus outside healthcare settings.