REACT-2: real-time assessment of community transmission – prevalence of coronavirus (COVID-19) antibodies in June 2020
Updated 11 August 2021
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Methodology
A representative cross-section of adult volunteers tested themselves with finger prick antibody stick tests (lateral flow immunoassay) between 20 June and 13 July 2020. The test results were read directly by participants and uploaded via an on-line survey.
Results
Prevalence of antibodies in the community in England was 6.0% (95% CI, 5.8, 6.1). This has been adjusted to take the performance of the device and sample distribution into account and represents 5,544 positive results from 109,076 participants.
Adjusted prevalence of infection in London is higher than in other regions at 13.0% (95% CI, 12.3, 13.6) with the South West having the lowest prevalence at 2.8 (95% CI, 2.4, 3.3).
People who work in care homes with client-facing roles had an adjusted prevalence of 16.5% compared with 11.7% for healthcare workers with direct patient contact and 5.3% for workers who were not key workers.
Those who had had contact with a confirmed case had an adjusted prevalence of 21.0% compared with 3.5% for people who had had no contact with a suspected or confirmed case.
Those who had had COVID-19 confirmed by a swab test had an adjusted antibody prevalence of 96.2% compared with 0.9% for people who had not had COVID-19 (either confirmed by test, suspected by a doctor or suspected by the individual themselves). Prevalence was highest in those with confirmed or suspected infection 60 to 90 days previously, and lower in those with more recent (<30 days) or older (>4 months) infection.
Those who reported severe symptoms at the time of suspected or confirmed infection had an adjusted prevalence of 28.7% compared with 13.7% (for people who had had no symptoms at the time of suspected or confirmed infection.
In those who had had suspected or confirmed Covid-19, adjusted prevalence of antibodies was highest for people who reported loss of sense of smell (53.5%) or taste (49.1%), loss of appetite (29.1%), severe fatigue (28.0%), diarrhoea (27.7%), and numbness or tingling somewhere in the body (28.1%).
The adjusted prevalence was slightly higher in males (6.2%) than females (5.8%).
There was an association between age and adjusted prevalence with the highest levels of 7.9% observed in young adults aged 18 to 24 years decreasing to the lowest levels of 3.2% in older adults aged 65 to 74. Black, Asian and other ethnicity was associated with higher adjusted prevalence at 17.3%, 11.9% and 12.3% respectively compared with white ethnicity at 5.0%.
There was an association between adjusted prevalence and household size ranging from 4.7% in single occupancy households to 13.0% in households with 7 or more occupants.
There was an association between adjusted prevalence and deprivation ranging from 5.0% in the least deprived areas to 7.3% in the most deprived areas.
People with no pre-existing health conditions had an adjusted prevalence of 5.3% compared with 4.9% for people with one or more pre-existing health conditions.
People who were overweight or obese had an adjusted prevalence of 5.2% and 5.4% respectively compared with 4.7% for people with normal weight status.
The adjusted prevalence was slightly higher in those who answered No to whether they currently smoke (5.2%) compared with those that answered Yes (3.2%).
Conclusion
During the period 20 June to 13 July 2020, SARS-CoV-2 antibodies were measured in the community at an overall adjusted prevalence of 6.0% in England.
Subsequent rounds of REACT-2 will allow accurate assessment of trends in antibody levels and how they vary across different population subgroups.
Background
Read the pre-print version of this report
Read the press release accompanying these findings
Read the findings from REACT-2 Study 1 – Performance
Read the findings from REACT-2 Study 2 and 3 – Acceptance and usability