Antibodies to SARS-CoV-2 protect against re-infection during outbreaks in care homes, September and October 2020
Anna Jeffery-Smith, Nalini Iyanger, Sarah Williams, J. Yimmy Chow, Felicity Aiano, Katja Höschler, Angie Lackenby, Joanna Ellis, Steven G. Platt, Shahjahan Miah, Kevin Brown, Gayatri Amirthalingam, Monika Patel, Mary Ramsay, Robin Gopal, André Charlett, Shamez Ladhani, Maria Zambon
Abstract
Two London care homes experienced a second COVID-19 outbreak, with 29/209 (13.9%) SARS-CoV-2 RT-PCR-positive cases (16/103 residents, 13/106 staff). In those with prior SARS-CoV-2 exposure, 1/88 (1.1%) individuals (antibody positive: 87; RT-PCR-positive: 1) became PCR-positive compared with 22/73 (30.1%) with confirmed seronegative status. After four months protection offered by prior infection against re-infection was 96.2% (95% confidence interval (CI): 72.7-99.5%) using risk ratios from comparison of proportions and 96.1% (95% CI: 78.8-99.3%) using a penalised logistic regression model.