Seroprevalence of antibodies to SARS-CoV-2 in healthcare workers: a cross-sectional study
Joseph E. Ebinger, Gregory J. Botwin, Christine M. Albert, Mona Alotaibi, Moshe Arditi, Anders H. Berg, Aleksandra Binek, Patrick Botting, Justyna Fert‐Bober, Jane C. Figueiredo, Jonathan Grein, Wohaib Hasan, Mir Henglin, Shehnaz K. Hussain, Mohit Jain, Sandy Joung, Michael Karin, Elizabeth H. Kim, Dalin Li, Yunxian Liu, Eric Luong, Dermot McGovern, Akil Merchant, Noah Merin, Peggy B. Miles, Margo Minissian, Trevor‐Trung Nguyen, Koen Raedschelders, Mohamad Rashid, Céline E. Riera, Richard V. Riggs, Sonia Sharma, Sarah Sternbach, Nancy Sun, Warren G. Tourtellotte, Jennifer E. Van Eyk, Kimia Sobhani, Jonathan Braun, Susan Cheng
Abstract
OBJECTIVE: We sought to determine the extent of SARS-CoV-2 seroprevalence and the factors associated with seroprevalence across a diverse cohort of healthcare workers. DESIGN: Observational cohort study of healthcare workers, including SARS-CoV-2 serology testing and participant questionnaires. SETTINGS: A multisite healthcare delivery system located in Los Angeles County. PARTICIPANTS: A diverse and unselected population of adults (n=6062) employed in a multisite healthcare delivery system located in Los Angeles County, including individuals with direct patient contact and others with non-patient-oriented work functions. MAIN OUTCOMES: Using Bayesian and multivariate analyses, we estimated seroprevalence and factors associated with seropositivity and antibody levels, including pre-existing demographic and clinical characteristics; potential COVID-19 illness-related exposures; and symptoms consistent with COVID-19 infection. RESULTS: We observed a seroprevalence rate of 4.1%, with anosmia as the most prominently associated self-reported symptom (OR 11.04, p<0.001) in addition to fever (OR 2.02, p=0.002) and myalgias (OR 1.65, p=0.035). After adjusting for potential confounders, seroprevalence was also associated with Hispanic ethnicity (OR 1.98, p=0.001) and African-American race (OR 2.02, p=0.027) as well as contact with a COVID-19-diagnosed individual in the household (OR 5.73, p<0.001) or clinical work setting (OR 1.76, p=0.002). Importantly, African-American race and Hispanic ethnicity were associated with antibody positivity even after adjusting for personal COVID-19 diagnosis status, suggesting the contribution of unmeasured structural or societal factors. CONCLUSION AND RELEVANCE: The demographic factors associated with SARS-CoV-2 seroprevalence among our healthcare workers underscore the importance of exposure sources beyond the workplace. The size and diversity of our study population, combined with robust survey and modelling techniques, provide a vibrant picture of the demographic factors, exposures and symptoms that can identify individuals with susceptibility as well as potential to mount an immune response to COVID-19.