COVID-19 Antibody Testing in Healthcare Workers in Arkansas

Introduction Seroprevalence surveys can estimate the cumulative incidence of SARS-CoV-2 infection in a symptom-independent manner, offering valuable data, including herd immunity, that can inform national and local public health policies. To our knowledge, there have been no large studies reporting seroprevalence in healthcare workers (HCWs) in the state of Arkansas. The objective of this study is to measure SARS-CoV-2 seroprevalence in HCWs in a large tertiary-care healthcare system prior to vaccine availability. Methods The Central Arkansas Veterans Healthcare System offered SARS-CoV-2 antibody testing prior to the widespread availability of vaccines. After Central Arkansas Veterans Healthcare System institutional review board (IRB) approval had been obtained, a retrospective chart review was used to identify all Central Arkansas Veterans Healthcare System HCWs who had undergone SARS-CoV-2 antibody testing from July 1, 2020, to September 30, 2020. Descriptive analysis was performed using Microsoft Excel (Microsoft Corporation, Redmond, Washington, United States). Correlation and regression tests were performed using SAS 9.4 software (SAS Institute Inc., Cary, NC). Results Over the study interval, 170 healthcare personnel had undergone SARS-CoV-2 anti-spike IgG antibody testing. Thirty-seven (21.8%) had positive antibody results. The 37 individuals were mostly women (94.5%), and the average age of the group was 47 years (range 29-69 years). The median antibody titers for those testing positive for antibodies were 10.8 units (range 1.1-58.5). Of the 37 people, 32 had a history of COVID-19 infection proven by reverse transcriptase polymerase chain reaction (RT-PCR). Conclusion Serologic testing is feasible for healthcare workers to document an immune response to a prior infection. In this study of HCWs, the rate of positivity among those tested was 21.8%. Data that do not incorporate the cohort of patients with prior infections will underestimate the impact of prior infections on herd immunity statistics and may misinform public policy.