S. Ladhani, A. Jeffery-Smith, Monika Patel, R. Janarthanan, J. Fok, E. Crawley-Boevey, A. Vusirikala, Elena Fernandez Ruiz De Olano, Marina Sanchez Perez, Suzanne Tang, K. Dun-Campbell, E. Evans, A. Bell, B. Patel, Z. Amin-Chowdhury, F. Aiano, K. Paranthaman, T. Ma, M. Saavedra-Campos, J. Ellis, M. Chand, K. Brown, M. Ramsay, S. Hopkins, N. Shetty, J. Chow, R. Gopal, M. Zambon
EClinicalMedicine, 2020
Background We investigated six London care homes experiencing a COVID-19 outbreak and found high rates of SARS-CoV-2 infection among residents and staff. Here we report follow-up investigations including antibody testing in the same care homes five weeks later. Methods Residents and staff in the initial investigation had a repeat nasal swab for SARS-CoV-2 RT-PCR and a blood test for SARS CoV-2 antibodies using ELISA based on SARS-CoV-2 native viral antigens derived from infected cells and virus neutralisation. Findings Of the 518 residents and staff in the initial investigation, 186/241 (77.2%) surviving residents and 208/254 (81.9%) staff underwent serological testing. Almost all SARS-CoV-2 RT-PCR positive residents and staff were seropositive five weeks later, whether symptomatic (residents 35/35, 100%; staff, 22/22, 100%) or asymptomatic (residents 32/33, 97.0%; staff 21/22, 95.5%). Symptomatic but SARS-CoV-2 RT-PCR negative residents and staff also had high seropositivity rates (residents 23/27, 85.2%; staff 18/21, 85.7%), as did asymptomatic RT-PCR negative individuals (residents 61/91, 67.0%; staff 95/143, 66.4%). Neutralising antibody was detected in 118/132 (89.4%) seropositive individuals and was not associated with age or symptoms. Ten residents (10/79 re-tested, 12.7%) remained RT-PCR positive but with higher RT-PCR cycle threshold values; 7/10 had serological testing and all were seropositive. New infections were detected in three residents and one staff. Interpretation RT-PCR provides a point prevalence of SARS-CoV-2 infection but significantly underestimates total exposure in outbreak settings. In care homes experiencing large COVID-19 outbreaks, most residents and staff had neutralising SARS-CoV-2 antibodies, which was not associated with age or symptoms. Funding PHE
Cited by 20 publications.
Field of study: Medicine