REACT-1: real-time assessment of community transmission of coronavirus (COVID-19) in August 2020

Published 11 September 2020

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This publication is available at https://www.gov.uk/government/publications/react-1-study-of-coronavirus-transmission-august-2020-results/react-1-real-time-assessment-of-community-transmission-of-coronavirus-covid-19-in-august-2020

Methodology

A representative cross-section of volunteers tested themselves with swabs between 22 August and 7 September 2020. Swabs were analysed using polymerase chain reaction (PCR).

Results

Overall adjusted prevalence of infection in the community was 0.126% (0.097%, 0.156%) This was adjusted for age, sex, ethnicity, region and area deprivation. Out of 152,909 swab results, 136 were positive. This was significantly higher than the prevalence of 0.04% (0.027%, 0.053%) measured during July 2020.

During the period 22 August to 7 September 2020 prevalence doubled every 7.7 (5.5, 12.7) days which is faster than in July 2020 where the prevalence was doubling every 14.2 (-58.6, 6.4) days.

The reproduction number R was estimated to be 1.7 (1.4, 2.0) which is higher than that measured during July 2020 at 1.3, (0.9, 1.8) and June 2020 at 0.6 (0.4, 0.8).

Prevalence of infection was highest in Yorkshire and the Humber and the North West at 0.17% (0.11, 0.27) and 0.17% (0.12, 0.24) respectively followed by 0.16% (0.80, 0.30) in the North East and 0.10% (0.06, 0.17) in London. The prevalence of infection increased in all regions between July 2020 and August 2020 with the biggest increase over this period seen in the North East.

There were no significant differences between the prevalence of infection for key workers and non-key workers. This is different from May 2020 when care workers and healthcare workers had increased risk of infection compared with those who were not key workers.

Recent contact with a known COVID-19 case (confirmed or tested) was associated with a higher prevalence at 2.74% (1.45, 5.12) than for no contact with a COVID-19 case at 0.08% (0.07, 0.10).

Black, Asian, mixed and other ethnicity was associated with higher prevalence of infection at 0.20%, 0.20%, 0.16% and 0.23% respectively compared with white ethnicity at 0.08%. Prevalence has increased across all ethnic groups since July 2020.

The highest rates of infection were at 0.25% (0.16%, 0.41%) in young adults aged 18 to 24 years, up from 0.08% in July. However the prevalence of infection increased across all age groups between July and August 2020.

65% of participants who tested positive did not report any symptoms at the time of swabbing or in the previous 7 days. This is similar to the proportion testing positive without symptoms in May (69%) and July (73%).

The prevalence was highest amongst those who reported classic COVID-19 symptoms (high temperature, new continuous cough, loss of smell or taste) at 0.68% (0.47%, 1.00%). This was significantly higher than for those reporting other symptoms at 0.10% (0.06%, 0.17%) or no symptoms at 0.07% (0.05%, 0.09%).

Conclusion

During the period 22 August to 7 September 2020, SARS-CoV-2 virus was circulating with relatively low prevalence but that prevalence was increasing at an accelerating rate through the period of testing.

Subsequent rounds of REACT-1 will allow accurate assessment of trends in prevalence and transmission.