SARS-CoV-2 antigen and antibody prevalence among UK staff working with cancer patients during the COVID-19 pandemic.

Favara, D. M.; McAdam, K.; Cooke, A.; Bordessa-Kelly, A.; Budriunaite, I.; Bossingham, S.; Houghton, S.; Doffinger, R.; Ainsworth, N.; Corrie, P.

Background International guidelines for testing potentially immunosuppressed cancer patients receiving non-surgical anticancer therapies for SARS-CoV-2 (COVID-19) are currently lacking. The value of routinely testing staff treating cancer patients is not known. Methods: Patient-facing oncology department staff at work during the COVID-19 pandemic consented to have a nasopharyngeal swab SARS-CoV-2 antigen test by polymerase chain reaction (PCR) and blood tests for SARS-CoV-2 antibody using a laboratory Luminex-based assay and a rapid point-of-care (POC) assay on 2 occasions 28 days apart in June and July 2020. Results 434 participants were recruited: nurses (58.3%), doctors (21.2%), radiographers (10.4%) and administrators (10.1%). 82% were female; median age 40-years (range 19-66). 26.3% reported prior symptoms suggestive of SARS-CoV-2 infection and 1.4% tested PCR-positive prior to June 2020. All were PCR-negative at both study day 1 and 28. 18.4% were SARS-CoV-2 sero-positive on day 1 by Luminex, of whom 42.5% also tested positive by POC. 47.5% of Luminex sero-positives had antibodies to both nucleocapsid (N) and surface (S) antigens. Nurses (21.3%) and doctors (17.4%) had higher prevalence trends of Luminex sero-positivity compared with administrators (13.6%) and radiographers (8.9%) (p=0.2). 38% of sero-positive participants reported previous symptoms suggestive of SARS-CoV-2 infection, a 1.9-fold higher odds than sero-negative participants (p=0.01). 400 participants re-tested on day 28: 13.3% were Luminex sero-positive of whom 92.5% were previously positive and 7.5% newly positive. Nurses (16.5%) had the highest seroprevalence trend amongst staff groups (p=0.07). 32.5% of day 1 sero-positives became sero-negative by day 28: the majority being previously reactive to the N-antigen only (p<0.0001). Conclusion The high prevalence of SARS-CoV-2 IgG sero-positivity in oncology nurses, and the high decline of positivity over 4 weeks supports regular antigen and antibody testing in this staff group for SARS-CoV-2 as part of routine patient care prior to availability of a vaccine.