TABLE 4.
Results of subgroup analyses of three‐dose vaccine effectiveness against Delta and Omicron variant related symptomatic COVID‐19 illness
| SARS‐CoV‐2 positive | SARS‐CoV‐2 negative | Unadjusted VE | Adjusted a VE | |||||
|---|---|---|---|---|---|---|---|---|
| Vaccinated/Total | (%) | Vaccinated/Total | (%) | VE | (95% CI) | VE | (95% CI) | |
| Delta | ||||||||
| High‐risk exposure | ||||||||
| No | 9/107 | (8) | 145/261 | (56) | 93 | (85 to 96) | 98 | (94 to 99) |
| Yes | 13/140 | (9) | 114/177 | (64) | 94 | (89 to 97) | 96 | (92 to 98) |
| Chronic medical condition | ||||||||
| No | 7/161 | (4) | 134/259 | (52) | 96 | (91 to 98) | 98 | (94 to 99) |
| Yes | 15/84 | (18) | 120/168 | (71) | 91 | (83 to 95) | 95 | (87 to 98) |
| Prior infection | ||||||||
| No | 20/228 | (9) | 239/378 | (63) | 94 | (91 to 97) | 97 | (95 to 99) |
| Yes | 1/17 | (6) | 20/60 | (33) | 87 | (−1 to 98) | 79 | (−81 to 98) |
| Days from illness onset to respiratory specimen collection | ||||||||
| 0–2 days | 17/206 | (8) | 212/355 | (60) | 94 | (90 to 96) | 97 | (94 to 99) |
| 3–10 days | 5/41 | (12) | 47/83 | (57) | 89 | (70 to 96) | 93 | (70 to 98) |
| Fever + cough/shortness of breath | ||||||||
| No | 9/72 | (13) | 131/195 | (67) | 93 | (85 to 97) | 95 | (86 to 98) |
| Yes | 13/175 | (7) | 128/243 | (53) | 93 | (87 to 96) | 97 | (94 to 99) |
| Omicron | ||||||||
| High‐risk exposure | ||||||||
| No | 111/218 | (51) | 199/253 | (79) | 72 | (58 to 81) | 76 | (61 to 86) |
| Yes | 211/324 | (65) | 209/278 | (75) | 38 | (12 to 57) | 49 | (23 to 66) |
| Chronic medical condition | ||||||||
| No | 201/378 | (53) | 266/360 | (74) | 60 | (45 to 71) | 66 | (50 to 76) |
| Yes | 117/159 | (74) | 131/160 | (82) | 38 | (−5 to 64) | 45 | (−4 to 71) |
| Prior infection | ||||||||
| No | 291/460 | (63) | 356/428 | (83) | 65 | (52 to 75) | 64 | (49 to 75) |
| Yes | 29/79 | (37) | 49/99 | (49) | 41 | (−8 to 68) | 52 | (−1 to 77) |
| Days from illness onset to respiratory specimen collection | ||||||||
| 0–2 days | 295/487 | (61) | 360/472 | (76) | 52 | (37 to 64) | 60 | (44 to 71) |
| 3–10 days | 27/55 | (49) | 48/59 | (81) | 78 | (49 to 90) | 72 | (18 to 91) |
| Fever + cough/shortness of breath | ||||||||
| No | 142/215 | (66) | 221/261 | (85) | 65 | (45 to 77) | 68 | (47 to 81) |
| Yes | 180/327 | (55) | 187/270 | (69) | 46 | (24 to 61) | 55 | (31 to 70) |
a
Logistic regression model adjusted for age, site, illness onset week, and prior infection status.