REACT-1: real-time assessment of community transmission of coronavirus (COVID-19) in February 2021
Updated 23 April 2021
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This publication is available at https://www.gov.uk/government/publications/react-1-study-of-coronavirus-transmission-february-2021-final-results/react-1-real-time-assessment-of-community-transmission-of-coronavirus-covid-19-in-february-2021
Methodology
A representative cross-section of volunteers tested themselves with swabs from 4 February to 13 February inclusive. Swabs were analysed using polymerase chain reaction (PCR).
Results
Swab results reported for the period 4 February to 13 February are referred to as round 9a. Swab results reported for the period 6 January to 22 January are referred to as round 8.
Over the 10 days of the partially completed round of testing, out of 85,473 swab results, 378 were positive, giving an overall weighted prevalence of 0.51% (95% CI, 0.45%, 0.59%) or 51 people per 10,000 infected. This represents a fall of more than two thirds since the previous (round 8 final) report where 1.57%, or 157 per 10,000 people were infected. Prevalence fell in the last half of the previous round, and this decline has continued into this current round.
Across the results for the latter half of round 8 (16 January to 22 January) and round 9a, a halving time of 14.6 (12.7, 17.1) days has been estimated, corresponding to R of 0.72 (0.69, 0.76)
Regional prevalence fell in all areas compared to the previous report in January. It was highest in the North West [1.38% to 0.91%] and North East (1.22% to 0.82%).There were substantial falls in prevalence compared to the last report in January in London (2.83% to 0.54%), West Midlands (1.66% to 0.33%), East of England (1.78% to 0.54%), South East (1.61% to 0.30%), East Midlands (1.16% to 0.51%). There was smaller fall in Yorkshire and The Humber (0.80% to 0.61%). Falls in regional prevalence are reflected in the regional R numbers, which are robustly below 1 in all regions other than the North East, North West and Yorkshire and The Humber.
There have been substantial falls in prevalence across all age groups between rounds 8 and 9a. The results now indicate that highest weighted prevalence is currently among 18 to 24 year olds at 0.89% (0.47%, 1.67%) and ages 5 to 12 years at 0.86% (0.60%, 1.24%). Lowest prevalence is among those 65 years and older at 0.30% (0.22%, 0.41%).
Large household size, living in a deprived neighbourhood and Asian ethnicity continue to be associated with increased prevalence, as do working in healthcare or care homes.
Conclusion
During the period 4 February to 13 February, SARS-CoV-2 virus was circulating with a lower prevalence than between 6 January to 22 January with 51 in 10,000 infected. There was strong evidence for a decline in prevalence averaged across the period 16 January to 22 January and 4 February to 13 February, with the most marked drop in regional prevalence evidenced in London.
Subsequent rounds of REACT-1 will allow further accurate assessment of trends in prevalence and transmission.