Prospective observational study and serosurvey of SARS-CoV-2 infection in asymptomatic healthcare workers at a Canadian tertiary care center

• DOI: 10.1371/journal.pone.0247258
• Publication Date: 2021-02-16T22:00:24Z
• Authors: Victor H. Ferreira; Andrzej Chruscinski; Vathany Kulasingam; Trevor J. Pugh; Tamara Dus; Brad Wouters; Amit Oza; Matthew Ierullo; Terrance Ku; Beata Majchrzak-Kita; Sonika T. Humar; Ilona Bahinskaya; Natalia Pinzon; Jianhua Zhang; Lawrence E. Heisler; Paul M. Krzyzanowski; Bernard Lam; Ilinca M. Lungu; Dorin Manase; Krista M. Pace; Pouria Mashouri; Michael Brudno; Michael Garrels; Tony Mazzulli; Myron Cybulsky; Atul Humar; Deepali Kumar
• Keywords: Canada; Science; Health Personnel; Q; R; COVID-19; COVID-19 Serological Testing; 3. Good health; Tertiary Care Centers; 03 medical and health sciences; 0302 clinical medicine; Seroepidemiologic Studies; COVID-19 Nucleic Acid Testing; Medicine; Humans; Asymptomatic Infections; Research Article

Health care workers (HCWs) are at higher risk for SARS-CoV-2 infection and may play a role in transmitting the infection to vulnerable patients and members of the community. This is particularly worrisome in the context of asymptomatic infection. We performed a cross-sectional study looking at asymptomatic SARS-CoV-2 infection in HCWs. We screened asymptomatic HCWs for SARS-CoV-2 via PCR. Complementary viral genome sequencing was performed on positive swab specimens. A seroprevalence analysis was also performed using multiple assays. Asymptomatic health care worker cohorts had a combined swab positivity rate of 29/5776 (0.50%, 95%CI 0.32–0.75) relative to a comparative cohort of symptomatic HCWs, where 54/1597 (3.4%) tested positive for SARS-CoV-2 (ratio of symptomatic to asymptomatic 6.8:1). SARS-CoV-2 seroprevalence among 996 asymptomatic HCWs with no prior known exposure to SARS-CoV-2 was 1.4–3.4%, depending on assay. A novel in-house Coronavirus protein microarray showed differing SARS-CoV-2 protein reactivities and helped define likely true positives vs. suspected false positives. Our study demonstrates the utility of routine screening of asymptomatic HCWs, which may help to identify a significant proportion of infections.