Real-world experience of SARS-CoV-2 antibody assays in UK healthcare workers

Background The seroprevalence of antibodies to SARS-CoV-2 in healthcare workers is variable throughout the world. This study compares the use of two antibody assays among large cohorts of healthcare workers in southern England. Methods This cohort study includes data obtained from staff at Western Sussex Hospitals NHS Foundation Trust (WSHT) and Brighton and Sussex University Hospitals (BSUH) during voluntary antibody testing, using Abbott and Roche SARS-CoV-2 antibody assays at each Trust respectively. Results The observed seroprevalence level was 7.9% for the WSHT/Abbott cohort versus 13% for the BSUH/Roche cohort. Based on a previous positive PCR, we find that the false-negative rate of the Abbott and Roche assays were 60.2% and 19% respectively, implying sensitivity levels of 39.8% and 81%. Within these cohorts, seropositivity was most strongly associated with those of South Asian ethnicity, allied health professionals and male sex (p<0.0001). Conclusions In this real-world study, neither antibody test performed to the specification level stated by the manufacturer. More rigorous testing of these and other assays in target populations is recommended prior to widespread usage if they are to provide data that might be useful to control the pandemic.