Table 2. Logistic regression analysis on risk of developing into COVID-19 pneumonia and serious COVID-19 by vaccination status, China, May 21, 2021–February 28, 2022.
| Variants |
Age
(years) |
Vaccination | Number of cases | COVID-19 pneumonia cases | Serious COVID-19 cases | ||||||
| N | n (%) | P value | OR (95% CI) | n (%) | Pvalue | OR (95% CI) | |||||
| Note: –: data not applicable.
Abbreviations: Ref=reference; OR=odds ratio; CI=confidence interval. | |||||||||||
| Delta | 3–17 | Unvaccinated | 540 | 169(31.3) | Ref | Ref | 1(0.2) | Ref | Ref | ||
| Partially vaccinated | 160 | 31(19.4) | <0.01 | 0.53(0.34–0.81) | 0(0) | − | − | ||||
| Full vaccination | 496 | 80(16.1) | <0.01 | 0.42(0.31–0.57) | 0(0) | − | − | ||||
| Subtotal | 1,196 | 280(23.4) | 1(0.1) | ||||||||
| 18–59 | Unvaccinated | 500 | 363(72.6) | Ref | Ref | 39(7.8) | Ref | Ref | |||
| Partially vaccinated | 428 | 286(66.8) | 0.06 | 0.76(0.57–1.01) | 12(2.8) | <0.01 | 0.34(0.16–0.68) | ||||
| Full vaccination | 4,233 | 2,392(56.5) | <0.01 | 0.49(0.40–0.60) | 59(1.4) | <0.01 | 0.17(0.11–0.26) | ||||
| Booster | 692 | 185(26.7) | <0.01 | 0.14(0.11–0.18) | 1(0.1) | <0.01 | 0.02(0.01–0.10) | ||||
| Subtotal | 5,853 | 3226(55.1) | 111(1.9) | ||||||||
| ≥60 | Unvaccinated | 445 | 402(90.3) | Ref | Ref | 133(29.9) | Ref | Ref | |||
| Partially vaccinated | 134 | 126(94.0) | 0.19 | 1.69(0.77–3.68) | 22(16.4) | <0.01 | 0.46(0.27–0.77) | ||||
| Full vaccination | 848 | 645(76.1) | <0.01 | 0.34(0.24–0.48) | 99(11.7) | <0.01 | 0.31(0.23–0.42) | ||||
| Booster | 53 | 30(56.6) | <0.01 | 0.14(0.07–0.26) | 2(3.8) | <0.01 | 0.09(0.01–0.36) | ||||
| Subtotal | 1,480 | 1,203(81.3) | 256(17.3) | ||||||||
| Omicron | 3–17 | Unvaccinated | 20 | 2(10.0) | Ref | Ref | 0(0) | Ref | Ref | ||
| Partially vaccinated | 20 | 4(20.0) | 0.36 | 2.34(0.38–14.57) | 0(0) | − | − | ||||
| Full vaccination | 444 | 59(13.3) | 0.63 | 1.44(0.32–6.37) | 0(0) | − | − | ||||
| Subtotal | 484 | 65(13.4) | 0(0) | ||||||||
| 18–59 | Unvaccinated | 56 | 18(32.1) | Ref | Ref | 0(0) | Ref | Ref | |||
| Partially vaccinated | 25 | 3(12.0) | 0.07 | 0.29(0.08–1.10) | 0(0) | − | − | ||||
| Full vaccination | 645 | 203(31.5) | 0.91 | 0.97(0.54–1.74) | 3(0.5) | 0.78 | − | ||||
| Booster | 675 | 192(28.4) | 0.57 | 0.84(0.47–1.52) | 2(0.3) | 0.83 | − | ||||
| Subtotal | 1,401 | 416(29.7) | 5(0.4) | ||||||||
| ≥60 | Unvaccinated | 39 | 31(79.5) | Ref | Ref | 4(10.3) | Ref | Ref | |||
| Partially vaccinated | 12 | 7(58.3) | 0.15 | 0.36(0.09–1.46) | 0(0) | 0.66 | 0.58(0–3.66) | ||||
| Full vaccination | 103 | 54(52.4) | 0.01 | 0.28(0.12–0.68) | 4(3.9) | 0.29 | 0.36(0.06–2.02) | ||||
| Booster | 68 | 39(57.4) | 0.02 | 0.35(0.14–0.87) | 0(0) | 0.03 | 0.10(0–0.61) | ||||
| Subtotal | 222 | 131(59.0) | 8(3.6) | ||||||||