Study population and setting
The goal of this study was to understand the serological prevalence of SARS-CoV-2 among healthcare workers in a tertiary care hospital in New York City, where there is a large amount of community transmission. Healthcare workers (n=285) volunteered to undergo serological (antibody) testing after at least 3 days with no COVID-19 symptoms. Participants who had experienced symptoms prior to enrollment did not undergo testing until at least 2 weeks symptoms onset, and 3 days without any symptoms. The study was conducted from March 24 to April 4, 2020, and collected age and sex demographic variables.
Summary of Main Findings
The average participant age was about 38 years (SD=10.8 years), and the majority of participants were men (n=111, 54%). Overall, 33% (n=93) of participants had positive antibody titers (defined as antibodies detected at dilutions greater than 1:320), and 3% (n=9) had weakly positive SARS-CoV-2 titers (defined as antibodies detected at dilutions of 1:50 to 1:160). Neither age nor sex showed any association with seroprevalence.
The study had a reasonable sample size to conduct the analyses. The study used a 14-day delay since symptom onset for participants to be tested in order to allow for antibodies to build in the system and be detectable.
The study was voluntary, which may be subject to selection bias among participants who were interested in learning their infection status, but who likely experienced minimal or mild symptoms that allowed them to present for testing. Healthcare workers who did not expect themselves to be exposed or infected were potentially less likely to self-refer for testing, potentially overestimating prevalence. The study also did not collect any other demographic or exposure-related variables, such as the department or specific occupation (e.g., physician, nurse, etc.) of their participants, or clinical variables such as symptoms experienced earlier.
This study demonstrated the prevalence of SARS-CoV-2 antibodies among healthcare workers in a tertiary care hospital across a number of departments.