Table 1. Unweighted and weighted prevalence (95% confidence interval) of swab positivity across four rounds of REACT-1.

Parameter	Round 1	Round 2	Round 3	Round 4
First sample	1 May 2020	19 June 2020	24 July 2020	20 August 2020
Last sample	1 June 2020	7 July 2020	11 August 2020	8 September 2020
Recruitment letters sent	395,000	600,000	710,000	710,000
Swabs sent	161,497	219,633	225,615	211,291
Tested swabs	120,620	159,199	161,560	154,325
Swab response rate	75%	72%	72%	73%
Overall response rate	31%	27%	23%	22%
Positive swabs	159	123	54	137
Unweighted prevalence (95% CI)	0.132% (0.113%, 0.154%)	0.077% (0.065%, 0.092%)	0.033% (0.025%, 0.043%)	0.089% (0.075%, 0.105%)
Weighted prevalence (95% CI)	0.156% (0.124%, 0.188%)	0.088% (0.068%, 0.109%)	0.040% (0.027%, 0.053%)	0.125% (0.096%, 0.154%)