Table 3.
Protection against any omicron BA.2 reinfection associated with pre-omicron or omicron BA.1 primary infection with or without vaccination, by time since last immunogenic event (vaccination or primary infection)
|
Pre-omicron primary infection |
Omicron BA.1 primary infection |
|||
|---|---|---|---|---|
| Unadjusted risk reduction* (95% CI) | Adjusted risk reduction*† (95% CI) | Unadjusted risk reduction* (95% CI) | Adjusted risk reduction*† (95% CI) | |
| Time since primary infection among unvaccinated participants | ||||
| 30–59 days (1 to <2 months) | NE | NE | 78% (43 to 91) | 82% (49 to 94) |
| 60–89 days (2 to <3 months) | NE | NE | 72% (59 to 82) | 76% (63 to 85) |
| 90–182 days (3 to <6 months) | 13% (−99 to 62) | 42% (−47 to 77) | 73% (66 to 79) | 70% (61 to 77) |
| 183–364 days (6 to <12 months) | 38% (5 to 60) | 39% (0 to 63) | NE | NE |
| 365–757 days (≥12 months) | 37% (16 to 53) | 42% (17 to 60) | NE | NE |
| Time since primary infection among participants with two vaccine doses | ||||
| 30–59 days (1 to <2 months) | NE | NE | 94% (88 to 97) | 97% (94 to 98) |
| 60–89 days (2 to <3 months) | NE | NE | 93% (90 to 95) | 97% (96 to 98) |
| 90–159 days (3 to <6 months) | NE | NE | 92% (91 to 94) | 96% (95 to 96) |
| Time since primary infection among participants with three vaccine doses | ||||
| 30–59 days (1 to <2 months) | NE | NE | 93% (89 to 95) | 96% (94 to 98) |
| 60–89 days (2 to <3 months) | NE | NE | 93% (91 to 95) | 97% (96 to 98) |
| 90–158 days (3 to <6 months) | NE | NE | 94% (92 to 95) | 96% (95 to 97) |
| Time since second vaccine dose among participants with two vaccine doses | ||||
| 7–59 days (<2 months) | 71% (48 to 84) | 89% (78 to 94) | NE | NE |
| 60–89 days (2 to <3 months) | 42% (18 to 59) | 73% (60 to 82) | NE | NE |
| 90–182 days (3 to <6 months) | 59% (50 to 66) | 77% (71 to 82) | NE | NE |
| 183–364 days (6 to <12 months) | 41% (32 to 48) | 68% (62 to 74) | NE | NE |
| Time since third vaccine dose among participants with three vaccine doses | ||||
| 7–59 days (<2 months) | 71% (55 to 80) | 88% (81 to 92) | 94% (90 to 97) | 98% (96 to 99) |
| 60–89 days (2 to <3 months) | 49% (39 to 57) | 80% (75 to 84) | 90% (78 to 96) | 95% (89 to 98) |
| 90–182 days (3 to <6 months) | 50% (44 to 56) | 72% (67 to 76) | NE | NE |
| 183–305 days (6 to <10 months) | 74% (−115 to 97) | 82% (−109 to 98) | NE | NE |
NE=not estimable.
*
Logistic regression models comparing participants with previous primary infection with or without vaccination versus unvaccinated participants without previous primary infection.
†
Estimates adjusted for age, sex, type of employment, facility, indication for testing, and epidemiological week.