Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

<h4>Background</h4>The relationship between the presence of antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the risk of subsequent reinfection remains unclear.<h4>Methods</h4>We investigated the incidence of SARS-CoV-2 infection confirmed by polymerase chain reaction (PCR) in seropositive and seronegative health care workers attending testing of asymptomatic and symptomatic staff at Oxford University Hospitals in the United Kingdom. Baseline antibody status was determined by anti-spike (primary analysis) and anti-nucleocapsid IgG assays, and staff members were followed for up to 31 weeks. We estimated the relative incidence of PCR-positive test results and new symptomatic infection according to antibody status, adjusting for age, participant-reported gender, and changes in incidence over time.<h4>Results</h4>A total of 12,541 health care workers participated and had anti-spike IgG measured; 11,364 were followed up after negative antibody results and 1265 after positive results, including 88 in whom seroconversion occurred during follow-up. A total of 223 anti-spike-seronegative health care workers had a positive PCR test (1.09 per 10,000 days at risk), 100 during screening while they were asymptomatic and 123 while symptomatic, whereas 2 anti-spike-seropositive health care workers had a positive PCR test (0.13 per 10,000 days at risk), and both workers were asymptomatic when tested (adjusted incidence rate ratio, 0.11; 95% confidence interval, 0.03 to 0.44; P = 0.002). There were no symptomatic infections in workers with anti-spike antibodies. Rate ratios were similar when the anti-nucleocapsid IgG assay was used alone or in combination with the anti-spike IgG assay to determine baseline status.<h4>Conclusions</h4>The presence of positive anti-spike or anti-nucleocapsid IgG antibodies was associated with a substantially reduced risk of SARS-CoV-2 reinfection in the ensuing 6 months. (Funded by the U.K. Government Department of Health and Social Care and others.).

Original publication




Journal article


The New England journal of medicine

Publication Date



From Oxford University Hospitals NHS Foundation Trust (S.F.L., N.E.S., P.C.M., S.C., T.J., F.W., L.W., D.A., A.-M.O., K.J.), Nuffield Department of Medicine (S.F.L., D.O., N.E.S., P.C.M., A.H., S.B.H., B.D.M., R.J.C., E.Y.J., D.I.S., G.S., D.E., S. Hoosdally, D.W.C., C.P.C., A.S.W., T.E.A.P., T.M.W.), the National Institute for Health Research (NIHR) Oxford Biomedical Research Centre (N.E.S., P.C.M., S. Hoosdally, D.W.C., A.S.W., T.E.A.P., D.W.E.), the Kennedy Institute of Rheumatology Research (B.D.M.), the Medical School, University of Oxford (L.J.P., T.G.R., Z.T.), Target Discovery Institute (D.E.), Nuffield Department of Population Health (A.-M.O., K.B.P., D.W.E.), and the Big Data Institute (D.W.E.), University of Oxford, and the NIHR Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance at University of Oxford in partnership with Public Health England (N.E.S., P.C.M., S. Hoosdally, D.W.C., K.B.P., A.S.W., T.E.A.P., D.W.E.), Oxford, and the National Infection Service, Public Health England at Colindale, London (M.C., S. Hopkins) - all in the United Kingdom; and the Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam (T.M.W.).


Oxford University Hospitals Staff Testing Group