A prospective study of asymptomatic SARS-CoV-2 infection among individuals involved in academic research under limited operations during the COVID-19 pandemic

• Published in: PloS one Vol. 17; no. 4; p. e0267353
• Main Authors: Pettifor, Audrey, DiPrete, Bethany L, Shook-Sa, Bonnie E, Premkumar, Lakshmanane, Kuczynski, Kriste, Dittmer, Dirk, Aiello, Allison, Wallet, Shannon, Maile, Robert, Tan, Joyce, Jadi, Ramesh, Pluta, Linda, de Silva, Aravinda M, Weber, David J, Kim, Min, Seña, Arlene C, Jones, Corbin D
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 25-04-2022; Public Library of Science (PLoS)
• Subjects: Analysis; Antigens; Assaying; Asymptomatic; Asymptomatic infection; Biology and life sciences; College campuses; Confidence intervals; Coronaviruses; COVID-19; COVID-19 - diagnosis; COVID-19 - epidemiology; COVID-19 diagnostic tests; Disease transmission; Epidemiology; Health risks; Humans; Immunology; Infections; Infectious diseases; Longitudinal Studies; Medical research; Medicine; Medicine and Health Sciences; Nucleocapsids; Pandemics; Polymerase chain reaction; Populations; Prospective Studies; Public health; Questionnaires; Research and Analysis Methods; Risk analysis; Risk factors; SARS-CoV-2 - genetics; Seroconversion; Seroepidemiologic Studies; Serological tests; Serology; Severe acute respiratory syndrome; Severe acute respiratory syndrome coronavirus 2; Subclinical infection; Universities and colleges; Viral diseases; United States; United States > US
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0267353

Early in the pandemic, transmission risk from asymptomatic infection was unclear, making it imperative to monitor infection in workplace settings. Further, data on SARS-CoV-2 seroprevalence within university populations has been limited.
We performed a longitudinal study of University research employees on campus July-December 2020. We conducted questionnaires on COVID-19 risk factors, RT-PCR testing, and SARS-CoV-2 serology using an in-house spike RBD assay, laboratory-based Spike NTD assay, and standard nucleocapsid platform assay. We estimated prevalence and cumulative incidence of seroconversion with 95% confidence intervals using the inverse of the Kaplan-Meier estimator.
910 individuals were included in this analysis. At baseline, 6.2% (95% CI 4.29-8.19) were seropositive using the spike RBD assay; four (0.4%) were seropositive using the nucleocapsid assay, and 44 (4.8%) using the Spike NTD assay. Cumulative incidence was 3.61% (95% CI: 2.04-5.16). Six asymptomatic individuals had positive RT-PCR results.
Prevalence and incidence of SARS-CoV-2 infections were low; however, differences in target antigens of serological tests provided different estimates. Future research on appropriate methods of serological testing in unvaccinated and vaccinated populations is needed. Frequent RT-PCR testing of asymptomatic individuals is required to detect acute infections, and repeated serosurveys are beneficial for monitoring subclinical infection.