The latest #REACT study from @imperialcollege shows a rapid fall in infection levels, by over two thirds since the last study.

Levels are now put at 0.51% (4/2 to 13/2), compared with 1.57% (6/1 to 22/1), and are still falling.

Let's look at the detail in this thread.
1/9

In Round 9a there were 85k tests carried out, with just 378 positives. Compare that to the 2,282 positives from the previous round with double the sample size. Positivity is now back at levels not seen since late September - good news!

2/9

R is estimated at 0.72 when compared with Round 8b, and this gives a halving time of around 15 days. (It's good to be talking about halving times now, not doubling times!)

If sustained, that would give a reduction of 75% every month.

3/9

Regionally the stand out feature is London. Whilst the fall is from an exceptionally high level, it's now "in the pack". The SE fall is also noticeable, given the proximity to London, something we've seen in ONS data too.

4/9

The modelled curves show the London fall clearly too.

However, the North East looks to be of some concern, with no obvious downward trend, and possibly even an upwards one. The confidence intervals are large though - inevitable as prevalence is lower.

5/9

All ages groups have fallen substantially, but particularly upper school ages and younger adults. We don't have modelled curves by age to give any additional insight unfortunately.

6/9

REACT always gives us some good demographic insight, easily visualised using this odds chart. The ethnicity data for R9a is interesting, with a reversal of the usual situation for some ethnic groups. Also note the increased risk for HCW's notably higher than in R8.

7/9

Table 3 in the Report (link below) gives the raw background data to the demographic analysis. As noted earlier, with much lower numbers, confidence intervals are now much greater once the data is subdivided.

8/9

https://spiral.imperial.ac.uk/bitstream/10044/1/86126/2/react1_r9_interim_preprint.pdf

As usual this interim report will be followed by a final report for Round 9 in due course. Thanks to all at @imperialcollege and their partners @Ipsosmori for this continuing survey which complements regular research by the ONS and Zoe to understand infection levels.
9/9