Declining prevalence of antibody positivity to SARS-CoV-2: a community study of 365,000 adults | medRxiv preprints (not peer reviewed)

Type Journal Article Author Helen Ward Author Graham Cooke Author Christina Atchison Author Matthew Whitaker Author Joshua Elliott Author Maya Moshe Author Jonathan C. Brown Author Barney Flower Author Anna Daunt Author Kylie Ainslie Author Deborah Ashby Author Christl Donnelly Author Steven Riley Author Ara Darzi Author Wendy Barclay Author Paul Elliott Author for the REACT study Team URL https://www.medrxiv.org/content/10.1101/2020.10.26.20219725v1 Rights © 2020, Posted by Cold Spring Harbor Laboratory. This pre-print is available under a Creative Commons License (Attribution-NonCommercial-NoDerivs 4.0 International), CC BY-NC-ND 4.0, as described at http://creativecommons.org/licenses/by-nc-nd/4.0/ Pages 2020.10.26.20219725 Publication medRxiv ISSN 2021-9725 Date 27/10/2020 Extra Publisher: Cold Spring Harbor Laboratory Press DOI 10.1101/2020.10.26.20219725 Accessed 2020-11-09 16:13:01 Library Catalog www.medrxiv.org Language en Abstract Background The prevalence and persistence of antibodies following a peak SARS-CoV-2 infection provides insights into its spread in the community, the likelihood of reinfection and potential for some level of population immunity. Methods Prevalence of antibody positivity in England, UK (REACT2) with three cross-sectional surveys between late June and September 2020. 365104 adults used a self-administered lateral flow immunoassay (LFIA) test for IgG. A laboratory comparison of LFIA results to neutralization activity in panel of sera was performed. Results There were 17,576 positive tests over the three rounds. Antibody prevalence, adjusted for test characteristics and weighted to the adult population of England, declined from 6.0% [5.8, 6.1], to 4.8% [4.7, 5.0] and 4.4% [4.3, 4.5], a fall of 26.5% [-29.0, −23.8] over the three months of the study. There was a decline between rounds 1 and 3 in all age groups, with the highest prevalence of a positive result and smallest overall decline in positivity in the youngest age group (18-24 years: −14.9% [-21.6, −8.1]), and lowest prevalence and largest decline in the oldest group (75+ years: −39.0% [-50.8, −27.2]); there was no change in antibody positivity between rounds 1 and 3 in healthcare workers (+3.45% [-5.7, +12.7]). The decline from rounds 1 to 3 was largest in those who did not report a history of COVID-19, (−64.0% [-75.6, −52.3]), compared to −22.3% ([-27.0, −17.7]) in those with SARS-CoV-2 infection confirmed on PCR. Discussion These findings provide evidence of variable waning in antibody positivity over time such that, at the start of the second wave of infection in England, only 4.4% of adults had detectable IgG antibodies using an LFIA. Antibody positivity was greater in those who reported a positive PCR and lower in older people and those with asymptomatic infection. These data suggest the possibility of decreasing population immunity and increasing risk of reinfection as detectable antibodies decline in the population. Short Title Declining prevalence of antibody positivity to SARS-CoV-2