Table 2.
Effectiveness of the ChAdOx1 nCoV-19 vaccine against SARS-CoV-2 infection and moderate-to-severe COVID-19
| Cases, n/N (%) | Controls, n/N (%) | Adjusted OR*(95% CI) | Effectiveness against infection (95% CI) | Moderate-to-severe COVID-19, n/N (%) | Mild COVID-19, n/N (%) | Adjusted OR*(95% CI) | Effectiveness against moderate-to-severe COVID-19 (95% CI) | |
|---|---|---|---|---|---|---|---|---|
| Effectiveness of two doses | ||||||||
| Unvaccinated | 2294/2379 (96·4%) | 1813/1981 (91·5%) | .. | .. | 83/84 (98·8%) | 2211/2295 (96·3%) | .. | .. |
| Complete vaccination | 85/2379 (3·6%) | 168/1981 (8·5%) | 0·37 (0·28–0·48) | 63·1% (51·5–72·1) | 1/84 (1·2%) | 84/2295 (3·7%) | 0·19 (0·01–0·90) | 81·5% (9·9–99·0) |
| Effectiveness of a single dose | ||||||||
| Unvaccinated | 2294/2451 (93·6%) | 1813/1994 (90·9%) | .. | .. | 83/87 (95·4%) | 2211/2364 (93·5%) | .. | .. |
| Single-dose vaccination | 157/2451 (6·4%) | 181/1994 (9·1%) | 0·54 (0·42–0·68) | 46·2% (31·6, 57·7) | 4/87 (4·6%) | 153/2364 (6·5%) | 0·20 (0·06–0·54) | 79·2% (46·1–94·0) |
OR=odds ratio.
*
OR adjusted for differences in age, sex, and risk of exposure to COVID-19-positive individuals.