Table 2. VE of 3-Dose Inactivated Vaccine vs 2-Dose Vaccine.
| Characteristic | Close contacts, No. (%) | VE (95% CrI) | ||||
|---|---|---|---|---|---|---|
| Individuals spreading infection with 2 doses [reference] | Individuals spreading infection with 3 doses | Crude | Adjusteda | |||
| Contact tested positive | Contact tested negative | Contact tested positive | Contact tested negative | |||
| Overall | 94 (1.4) | 6536 (98.6) | 321 (0.8) | 40 360 (99.2) | 44.7 (30.3 to 56.1) | 28.9 (7.7 to 45.2) |
| Sex of individual spreading infection | ||||||
| Male | 54 (1.6) | 3666 (98.4) | 138 (1.0) | 13 439 (99.0) | 30.3 (4.3 to 49.2) | 28.4 (−4.9 to 51.3) |
| Female | 40 (1.4) | 2870 (98.6) | 183 (0.7) | 26 921 (99.3) | 51.2 (31.2 to 65.4) | 18.4 (−15.9 to 44.1) |
| Age of individual spreading infection, y | ||||||
| 0-15 | 54 (2.5) | 2077 (97.5) | 0 | 0 | NAb | NAb |
| 16-65 | 31 (0.8) | 3988 (99.2) | 302 (0.8) | 39 716 (99.2) | 2.2 (−29.3 to 67.5) | 3.3 (−32.9 to 29.8) |
| >65 | 9 (1.9) | 471 (98.1) | 19 (2.9) | 644 (97.1) | −35.2 (−70.9 to 30.8) | −34.0 (−70.7 to −32.7) |
| Time since last vaccine dose for individual spreading infection, d | ||||||
| 15-90 | 3 (1.3) | 222 (98.7) | 13 (1.1) | 1225 (98.9) | 21.5 (−64.0 to 77.8) | 48.5 (23.9 to 61.4) |
| 91-180 | 9 (1.0) | 862 (99.0) | 46 (0.9) | 5138 (99.1) | 14.3 (−43.1 to 58.2) | 13.2 (−44.7 to 58.3) |
| ≥180 | 82 (1.5) | 5452 (98.5) | 262 (0.8) | 33 997 (99.2) | 48.8 (34.2 to 60.1) | 19.7 (−4.4 to 38.3) |
| Symptom status of individual spreading infection | ||||||
| Symptomatic | 8 (0.5) | 1668 (99.5) | 8 (1.0) | 802 (99.0) | −51.9 (−82.0 to 22.3) | −32.0 (−89.4 to 77.1) |
| Asymptomatic | 86 (1.7) | 4868 (98.3) | 313 (0.8) | 39 558 (99.2) | 55.2 (43.0 to 64.8) | 34.9 (15.1 to 50.1) |
| Contact setting | ||||||
| Household | 62 (19.1) | 267 (80.9) | 154 (13.4) | 990 (86.6) | 33.0 (7.3 to 51.6) | 39.1 (12.7 to 57.5) |
| Nonhousehold | 32 (0.5) | 6269 (99.5) | 167 (0.4) | 39 370 (99.6) | 16.9 (−17.6 to 43.1) | 8.1 (−27.5 to 38.8) |
Abbreviations: CrI, credible interval; NA, not applicable; VE, vaccine effectiveness.
a
Variables adjusted in the model were sex, age of individuals who spread the infection and got infected, last exposed calendar date of contacts, importation status of individual spreading the infection, contact setting, and vaccine status of individual getting infected.
b
These estimates were not calculated owing to insufficient sample size, which led to noninformatively wide 95% CrIs.