Incidence and Prevalence of Coronavirus Disease 2019 Within a Healthcare Worker Cohort During the First Year of the Severe Acute Respiratory Syndrome Coronavirus 2 Pandemic
Sarah B. Doernberg, Marisa Holubar, Vivek Jain, Yingjie Weng, Di Lu, Jenna Bollyky, Hannah A. Sample, Beatrice Huang, Charles S. Craik, Manisha Desai, George W. Rutherford, Yvonne Maldonado, Parul Bhargava, Markus‐Frederik Bohn, Jessica Chao, Charles S. Craik, Sarah B. Doernberg, Jacob S. Ghahremani, David V. Glidden, Ralph Gonzales, Beatrice Huang, Sravya Jaladanki, Aida Julien, Daniel H. Lowenstein, Steve Miller, Audrey Mustoe, Marcus Paoletti, George W. Rutherford, Hannah A. Sample, Rodolfo Villa, Emerald Wan, Aimee Williams, Lillian B. Brown, Jessica Chuang, Vivek Jain, Carina Marquez, Guntas Padda, Luis Rubio, Daisy Valdivieso, Rosebay Abad, Anthony Bet, Jenna Bollyky, Manisha Desai, Jeffrey Wing‐Hong Fung, Anna Graber, Cole Holderman, Marisa Holubar, Hannah Kelley, Amanda Kempema, Christina Kong, Christopher Leung, J. Lohmann, Di Lu, Yvonne Maldonado, Lloyd B. Minor, Lorena Orozco, Benjamin A. Pinsky, Jamie Saxeena, Matthew Sklar, Hilary Tang, Jasmine Wiese, Yingjie Weng, Emily Crawford, Joe DeRisi
Abstract
BACKGROUND: Preventing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2_ infections in healthcare workers (HCWs) is critical for healthcare delivery. We aimed to estimate and characterize the prevalence and incidence of coronavirus disease 2019 (COVID-19) in a US HCW cohort and to identify risk factors associated with infection. METHODS: We conducted a longitudinal cohort study of HCWs at 3 Bay Area medical centers using serial surveys and SARS-CoV-2 viral and orthogonal serological testing, including measurement of neutralizing antibodies. We estimated baseline prevalence and cumulative incidence of COVID-19. We performed multivariable Cox proportional hazards models to estimate associations of baseline factors with incident infections and evaluated the impact of time-varying exposures on time to COVID-19 using marginal structural models. RESULTS: A total of 2435 HCWs contributed 768 person-years of follow-up time. We identified 21 of 2435 individuals with prevalent infection, resulting in a baseline prevalence of 0.86% (95% confidence interval [CI], .53%-1.32%). We identified 70 of 2414 incident infections (2.9%), yielding a cumulative incidence rate of 9.11 cases per 100 person-years (95% CI, 7.11-11.52). Community contact with a known COVID-19 case was most strongly correlated with increased hazard for infection (hazard ratio, 8.1 [95% CI, 3.8-17.5]). High-risk work-related exposures (ie, breach in protective measures) drove an association between work exposure and infection (hazard ratio, 2.5 [95% CI, 1.3-4.8). More cases were identified in HCWs when community case rates were high. CONCLUSIONS: We observed modest COVID-19 incidence despite consistent exposure at work. Community contact was strongly associated with infections, but contact at work was not unless accompanied by high-risk exposure.