REACT-1: real-time assessment of community transmission of coronavirus (COVID-19) in November 2020
Published 15 December 2020
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This publication is available at https://www.gov.uk/government/publications/react-1-study-of-coronavirus-transmission-november-2020-final-results/react-1-real-time-assessment-of-community-transmission-of-coronavirus-covid-19-in-november-2020
Methodology
A representative cross-section of volunteers tested themselves with swabs from 13 November to 3 December, inclusive. Swabs were analysed using polymerase chain reaction (PCR).
Results
Over the 21 days of the completed round of testing, out of 168,182 swab results, 1299 were positive. The overall weighted national prevalence of infection in the community was 0.94% or 94 per 10,000.
Swab results reported for the period 13 November to 24 November are referred to as round 7a. Swab results reported for the period 25 November to 3 December are referred to as round 7b.
In round 7b (25 November to 3 December), out of 63,059 swab results, 478 were positive. The overall weighted national prevalence of infection in the community was 0.91% or 91 people per 10,000 infected, down slightly from the 96 people per 10,000 infected in the last report (13 November to 24 November). For the period overall (13 November to 3 December), the estimated R number is close to 1 at 0.96 (0.88, 1.03). The decline in prevalence noted in round 7a (13 November to 24 November) is no longer apparent, with a flattening of the national epidemic curve in the round 7b data.
The highest prevalence is now in Yorkshire and The Humber where between rounds 7a ((13 November to 24 November) and 7b (25 November to 3 December) it rose from 1.17% to 1.39%. There was also a rise of prevalence during this period in London from 0.98% to 1.21%, and North East from 0.72% to 1.26%. There was a halving of prevalence in the West Midlands to 0.71%, and a decline in the East Midlands to 1.04% and in North West to 0.92%.
At the regional level, R numbers for round 7 overall ranged from 0.60 (0.41, 0.80) for the West Midlands, up to 1.27 (1.04, 1.54) for London. Comparing round 7a (13 November to 24 November) to 7b (25 November to 3 December) there are local areas in all regions where prevalence rates appear to be increasing, especially in the east of the country. In London, prevalence is increasing most in the east and south east.
Patterns of national weighted prevalence by age group show highest levels in school-aged children. At ages 13 to 17 years prevalence is now 2.08% (1.50%, 2.89%) and at ages 5 to 12 years it is 1.70% (1.20%, 2.40%). Nationally, there have been large apparent falls in prevalence between rounds 7a and 7b in 18 to 24-year olds, and suggestion of levelling off in those aged 55 years and over.
In round 7b (25 November to 3 December), patterns of swab-positivity by ethnicity and key worker status are similar to those in round 7a (13 November to 24 November). In round 7b, swab-positivity in people of Asian and Other ethnicities is 1.94% and 2.58% respectively, compared with 0.80% in white people. In round 7b, prevalence in health care workers and care home workers is 1.66% compared with 0.71% (0.59%, 0.86%) in other workers.
Conclusion
During the period 25 November to 3 December, SARS-CoV-2 virus was circulating with a slightly lower prevalence than between 13 November to 24 November with 91 in 10,000 infected.
Subsequent rounds of REACT-1 will allow further accurate assessment of trends in prevalence and transmission.
Background
Read the pre-print version of this report.