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

• Published in: PloS one Vol. 16; no. 2; p. e0247258
• Main Authors: Ferreira, Victor H., Chruscinski, Andrzej, Kulasingam, Vathany, Pugh, Trevor J., Dus, Tamara, Wouters, Brad, Oza, Amit, Ierullo, Matthew, Ku, Terrance, Majchrzak-Kita, Beata, Humar, Sonika T., Bahinskaya, Ilona, Pinzon, Natalia, Zhang, Jianhua, Heisler, Lawrence E., Krzyzanowski, Paul M., Lam, Bernard, Lungu, Ilinca M., Manase, Dorin, Pace, Krista M., Mashouri, Pouria, Brudno, Michael, Garrels, Michael, Mazzulli, Tony, Cybulsky, Myron, Humar, Atul, Kumar, Deepali
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 16.02.2021; Public Library of Science (PLoS)
• Subjects: Asymptomatic Infections - epidemiology; Biology and life sciences; Canada; COVID-19 - diagnosis; COVID-19 - epidemiology; COVID-19 Nucleic Acid Testing - statistics & numerical data; COVID-19 Serological Testing - statistics & numerical data; Demographic aspects; Health Personnel - statistics & numerical data; Humans; Medical examination; Medical personnel; Medical screening; Medicine and health sciences; People and Places; Research and Analysis Methods; Seroepidemiologic Studies; Tertiary Care Centers - statistics & numerical data; Canada
• ISSN: 1932-6203; 1932-6203
• DOI: 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.