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

• Main 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
• Format: Article
• Language: English
• Published: Public Library of Science (PLoS) 2021-01-01
• Series: PLoS ONE
• Online Access: https://doi.org/10.1371/journal.pone.0247258

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.