Alliance for Pandemic Preparedness

April 13, 2021

SARS-CoV-2 Infection Rates of Antibody-Positive Compared with Antibody-Negative Health-Care Workers in England: A Large, Multicentre, Prospective Cohort Study (SIREN)

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  • Prior SARS-CoV-2 infection was associated with an 84% lower risk of new infection according to the SIREN Study, a large multi-center prospective study conducted in the UK from June to December 2020. During the study period, 155 potential reinfections were detected among 8,278 participants positive at baseline compared to 1,704 new PCR positive infections detected among 17,383 participants negative at baseline. This corresponds to 7.6 infections per 100,000 person-days in the positive cohort, compared to 57.3 infections per 100,00 person-days in the negative cohort. Participants attended regular PCR (every 2 weeks) and antibody (every 4 weeks) testing and completed symptom and exposure questionnaires every 2 weeks. Although the B.1.1.7 variant was circulating during the final part of the study period, causing roughly 50% of infections, the authors did not find evidence that reinfection rates increased with increasing prevalence of B.1.1.7 infections.

Hall et al. (Apr 9, 2021). SARS-CoV-2 Infection Rates of Antibody-Positive Compared with Antibody-Negative Health-Care Workers in England: A Large, Multicentre, Prospective Cohort Study (SIREN). The Lancet. https://doi.org/10.1016/S0140-6736(21)00675-9