Our latest results from the REACT-1 study show that prevalence of #COVID19 is increasing in England. Main results are highlighted below.
The full (not yet peer reviewed) pre-print is available here: https://tinyurl.com/y3jw765x  (1/n)

@SRileyIDD @DrCWalters @eales96 @HaoweiWang7

The epidemic declined between rounds 1 and 2, and 2 and 3, but was increasing between rounds 3 and 4: doubling time 17 (13, 23) days and R=1.3 (1.2, 1.4)

From the most recent round 4 data (22nd August and 7th September): doubling time 7.7 (5.5, 12.7) days and R=1.7 (1.4, 2.0)

Over all four rounds of the study, we found that 72% (67%, 76%) of swab-positive individuals were asymptomatic at the time of swab and in the week prior.

Our data were suggestive of a higher rate of asymptomatic swab-positivity in children compared to adults.

Cycle threshold values* were lower (viral loads were higher) for rounds 1 and 4 than they were for rounds 2 and 3.
*Cycle threshold values reflect the amount of virus in a positive sample, with high CT values corresponding to low levels of virus.

In round 4, we observed:
- highest prevalence in 18 to 24 age group at 0.25% (0.16%, 0.41%), increasing from 0.08% (0.04%, 0.18%) in round 3.
- lowest prevalence in 65+ at 0.04% (0.02%, 0.06%)

Participants of Asian ethnicity had elevated odds of infection.

We identified clusters in and around London, transient clusters in the Midlands, and an expanding area of clustering in the North West and more recently in Yorkshire and the Humber.

Interpretation:
Low levels of transmission persisted in England in mid-summer 2020, but the prevalence of SARS-CoV-2 is now increasing.

We found evidence of accelerating transmission at the end of August and beginning of September 2020.

Studies like REACT-1 (representative community antigen sampling)
- can increase situational awareness
- be used as an early warning system
- be used to rapidly evaluate success of policies in keeping the virus controlled at low prevalence