Published on Thu Jul 22 2021

Increasing SARS-CoV-2 antibody prevalence in England at the start of the second wave: REACT-2 Round 4 cross-sectional study in 160,000 adults

Ward, H., Atchison, C. J., Whitaker, M., Donnelly, C. A., Riley, S., Ashby, D., Darzi, A., Barclay, W., Cooke, G., Elliott, P.

Overall adjusted and weighted prevalence was 5.6% (95% CI 5.4-5.7) This was an increase from 4.4% (4.3-4.5) in round 3 (September) Largest increase by age was in the 18 to 24 year old age group. Highest prevalence in people of Bangladeshi 15.1% (10.9-20.5), Pakistani 13.9% (11.2-17.2) and African 13.5%.

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Abstract

Background: REACT-2 Study 5 is a population survey of the prevalence of SARS-CoV-2 antibodies in the community in England. Methods: We contacted a random sample of the population by sending a letter to named individuals aged 18 or over from the NHS GP registrations list. We then sent respondents a lateral flow immunoassay (LFIA) kit for SARS-CoV-2 antibody self-testing and asked them to perform the test at home and complete a questionnaire, including reporting of their test result. Overall, 161,537 adults completed questionnaires and self-administered LFIA tests for IgG against SARS-CoV-2 between 27 October and 10 November 2020. Results: The overall adjusted and weighted prevalence was 5.6% (95% CI 5.4-5.7). This was an increase from 4.4% (4.3-4.5) in round 3 (September), a relative increase of 26.9% (24.0-29.9).The largest increase by age was in the 18 to 24 year old age group, which increased (adjusted and weighted) from 6.7% (6.3-7.2) to 9.9% (9.3-10.4), and in students, (adjusted, unweighted) from 5.9% (4.8-7.1) to 12.1% (10.8-13.5). Prevalence increased most in Yorkshire and The Humber, from 3.4% (3.0-3.8) to 6.3% (5.9-6.8) and the North West from 4.5% (4.2-4.9) to 7.7% (7.2-8.1). In contrast, the prevalence in London was stable, at 9.5% (9.0-9.9) and 9.5% (9.1-10.0) in rounds 3 and 4 respectively. We found the highest prevalence in people of Bangladeshi 15.1% (10.9-20.5), Pakistani 13.9% (11.2-17.2) and African 13.5% (10.7-16.8) ethnicity, and lowest in those of white British ethnicity at 4.2% (4.0-4.3). Interpretation: The second wave of infection in England is apparent in increasing antibody prevalence, particularly in younger people, students, and in the Northern Regions. By late October a large proportion of the population remained susceptible to SARS-CoV-2 infection in England based on naturally acquired immunity from the first and early second wave.