Table 4. Crude and adjusted vaccine effectiveness estimates for influenza by age group and subtype, test–negative case–control study, in those aged 65 years and older, United Kingdom, influenza seasons 2010/11–2016/17.
| Type/Subtype | Age group | Cases | Controls | Crude VE (95% CI) |
Adjusteda VE (95% CI) |
||
|---|---|---|---|---|---|---|---|
| Unvacc | Vacc | Unvacc | Vacc | ||||
| A or B | All ≥ 65 years | 118 | 276 | 551 | 1151 | - 12.0 (- 42.1 to 11.8) | 32.5 (11.6 to 48.5) |
| 65–74 years | 87 | 157 | 370 | 714 | 17.0 (- 10.0 to 37.4) | 45.2 (25.1 to 60) | |
| 75–84 years | 14 | 88 | 134 | 353 | - 138.6 (- 333.9 to -31.2) | - 26.3 (- 149.3 to 36.0) | |
| ≥ 85 years | 6 | 31 | 47 | 84 | - 189.1 (- 643.2 to - 12.4) | - 3.2 (- 237.8 to 68.5) | |
| A(H1)pdm09 | All ≥ 65 years | 33 | 38 | 551 | 1151 | 44.9 (11.2 to 65.8) | 60.8 (33.9 to 76.7) |
| 65–74 years | 28 | 25 | 370 | 714 | 53.7 (19.5 to 73.4) | 68.4 (41.7 to 82.9) | |
| 75–84 years | 2 | 11 | 134 | 353 | - 108.8 (- 854.3 to 54.3) | - 40.8 (- 643.7 to 73.3) | |
| ≥ 85 years | 3 | 2 | 47 | 84 | NA | NA | |
| A(H3N2) | All ≥ 65 years | 47 | 173 | 551 | 1151 | - 76.2 (- 147.1 to - 25.7) | 5.6 (- 39.2 to 35.9) |
| 65–74 years | 37 | 91 | 370 | 714 | - 27.5 (- 90.6 to 14.8) | 23.3 (- 20.9 to 51.4) | |
| 75–84 years | 7 | 58 | 134 | 353 | - 214.5 (- 606.4 to - 40.1) | - 40.9 (- 264.2 to 45.5) | |
| ≥ 85 years | 3 | 24 | 47 | 84 | - 347.6 (- 1465.8 to - 28.0) | - 91.0 (- 806.6 to 59.8) | |
| B | All ≥ 65 years | 41 | 60 | 551 | 1151 | 30.0 (- 5.6 to 53.5) | 50.0 (21.6 to 68.1) |
| 65–74 years | 36 | 40 | 370 | 714 | 42.4 (8.1 to 63.9) | 57.9 (29.8 to 74.7) | |
| 75–84 years | 5 | 16 | 134 | 353 | - 21.5 (- 238.1 to 56.4) | 33.3 (- 110.9 to 78.9) | |
| ≥ 85 years | 0 | 4 | 47 | 84 | NA | NA | |
CI: confidence interval; NA: Not available; Unvacc: unvaccinated; Vacc: vaccinated.
aAdjusted for age group, sex, season, month and surveillance scheme.
Numbers too small to estimate are indicated by NA.