Table 2. Fitted growth rates, reproduction numbers, and doubling times (95% credible intervals) for SARS-CoV-2 swab positivity in England.
| Data | Round(s)* |
Number of participants or cases |
Growth rate r (per day) |
P (r > 0) |
Reproduction number |
Doubling (+) or halving (−) time (days) |
| REACT All | 1 | 110,944 | −0.077 (−0.107, −0.046) | <0.01 | 0.57 (0.44, 0.73) | −9.0 (−6.5, −14.9) |
| 2 | 157,428 | −0.089 (−0.130, −0.032) | <0.01 | 0.52 (0.36, 0.81) | −7.8 (−5.3, −21.4) | |
| 3 | 162,619 | 0.049 (−0.012, 0.109) | 0.94 | 1.34 (0.93, 1.83) | 14.2 (−58.6, 6.4) | |
| 4 | 153,964 | 0.086 (0.050, 0.122) | >0.99 | 1.64 (1.35, 1.95) | 8.0 (13.8, 5.7) | |
| 1 and 2 | 268,422 | −0.018 (−0.025, −0.012) | <0.01 | 0.89 (0.85, 0.92) | −37.9 (−28.0, −57.5) | |
| 2 and 3 | 320,047 | −0.025 (−0.034, −0.017) | <0.01 | 0.85 (0.79, 0.90) | −27.3 (−20.1, −41.6) | |
| 3 and 4 | 316,583 | 0.041 (0.030, 0.051) | >0.99 | 1.28 (1.20, 1.36) | 17.0 (22.8, 13.5) | |
| Routine surveillance data | 1 | 69,299 | −0.034 (−0.042, −0.027) | <0.01 | 0.80 (0.75, 0.84) | −20.3 (−16.7, −26.0) |
| 2 | 11,523 | −0.018 (−0.032, −0.004) | 0.01 | 0.89 (0.81, 0.97) | −38.5 (−21.9, −164.1) | |
| 3 | 15,172 | 0.026 (0.004, 0.049) | 0.99 | 1.18 (1.03, 1.34) | 26.2 (161.4, 14.2) | |
| 4 | 31,209 | 0.085 (0.067, 0.104) | >0.99 | 1.63 (1.48, 1.79) | 8.1 (10.3, 6.7) | |
| 1 and 2 | 97,255 | −0.029 (−0.031, −0.027) | <0.01 | 0.82 (0.81, 0.84) | −23.7 (−22.0, −25.7) | |
| 2 and 3 | 36,393 | 0.007 (0.003, 0.012) | >0.99 | 1.05 (1.02, 1.07) | 93.6 (207.6, 60.6) | |
| 3 and 4 | 56,064 | 0.029 (0.023, 0.035) | >0.99 | 1.19 (1.15, 1.24) | 24.1 (30.7, 20.1) |
*See Table 1 for start and end dates of rounds