Table 3. Effectiveness of CoronaVac Vaccine in Preventing Covid-19 Outcomes among Cohort Participants 60 Years of Age or Older, According to Immunization Status.
| Outcome and Immunization Status | Subgroup Cohort | Persons with Covid-19 | Vaccine Effectiveness (95% CI) | |||
|---|---|---|---|---|---|---|
| No. of Person-Days |
No. of Persons |
Incidence Rate |
Analysis Adjusted for Sex and Age |
Analysis Adjusted for All Covariates* |
Stratified Analysis† |
|
| no. of events/ 1000 person-days |
percent | |||||
| Covid-19 | ||||||
| Unvaccinated | 75,707,905 | 15,597 | 0.2060 | — | — | — |
| Partially immunized | 35,675,604 | 8,333 | 0.2336 | 3.9 (0.9–6.8) |
9.7 (6.9–12.4) |
12.7 (9.8–15.5) |
| Fully immunized | 66,563,272 | 7,510 | 0.1128 | 63.4 (62.0–64.6) |
66.6 (65.4–67.8) |
67.2 (66.0–68.4) |
| Hospitalization | ||||||
| Unvaccinated | 76,047,640 | 5,304 | 0.0697 | — | — | — |
| Partially immunized | 35,961,593 | 2,168 | 0.0603 | 29.2 (25.1–33.1) |
35.0 (31.3–38.6) |
38.6 (34.8–42.2) |
| Fully immunized | 66,986,859 | 1,344 | 0.0201 | 83.4 (82.2–84.5) |
85.3 (84.3–86.3) |
85.4 (84.3–86.4) |
| Admission to ICU | ||||||
| Unvaccinated | 76,194,648 | 1,811 | 0.0238 | — | — | — |
| Partially immunized | 36,062,081 | 672 | 0.0186 | 38.2 (31.9–44.0) |
44.5 (38.7–49.7) |
47.0 (41.2–52.2) |
| Fully immunized | 67,051,769 | 331 | 0.0049 | 87.5 (85.7–89.0) |
89.2 (87.6–90.6) |
89.3 (87.8–90.7) |
| Confirmed death | ||||||
| Unvaccinated | 76,169,386 | 1,999 | 0.0262 | — | — | — |
| Partially immunized | 36,053,806 | 768 | 0.0213 | 39.7 (33.8–45.1) |
45.8 (40.4–50.7) |
46.1 (40.5–51.2) |
| Fully immunized | 67,045,620 | 402 | 0.0060 | 84.4 (82.3–86.2) |
86.5 (84.6–88.1) |
86.8 (85.0–88.4) |
*
The analysis was adjusted for age, sex, region of residence, income, nationality, and whether the patient had underlying conditions that have been associated with severe Covid-19.
†
A stratified version of the extended Cox proportional-hazards model was fit to test the robustness of the estimates to model assumptions, with stratification according to sex, age, coexisting conditions, nationality, and income.