Table 3.
Effectiveness of influenza vaccine in community-dwelling elderly people
| Outcome and studies | Study period | Risk status | Effectiveness (%; 95%CI) |
|---|---|---|---|
| Hospital admission for pneumonia and influenza | |||
| Retrospective cohort | 1980–81 to | Low | 40 (1 to 64) |
| study84 | 1988–89 | High | 30 (17 to 42) |
| Retrospective cohort | 1990–91 to | Low | 49 (29 to 69) |
| study85 | 1995–96 | Intermediate | 32 (−8 to 71) |
| High | 29(11 to 47) | ||
| Retrospective cohort | 1996–97 | Elderly | 20 (5 to 31) |
| study86 | 1997–98 | 24 (14 to 34) | |
| Case-control study87 | 1982–83 | Elderly | 37 (15 to 53) |
| 1985–86 | 39 (19 to 53) | ||
| Case-control study88 | 1989–90 | Elderly | 63 (17 to 84) |
| Case-control study89 | 1989–90 | Elderly | 45 (14–64) |
| Case-control study90 | 1990–91 | Elderly | 31 (4 to 51) |
| 1991–92 | 32 (7 to 50) | ||
| Case-control study91 | 1994–95 | Elderly | 79 (45 to 91) |
| Case-control study92 | 1994–95 | Elderly | 33 (5 to 52) |
| All respiratory admissions | |||
| Retrospective cohort | 1990–91 to | Elderly | 32 (29 to 40) |
| study85 | 1995–96 | ||
| Case-control study87 |
1982–83 |
Elderly |
17 (1 to 32) |
| 1985–86 | 32 (20 to 43) | ||
| All respiratory admissions and heart failure | |||
| Retrospective cohort | 1994–95 to | Elderly | 20 (10–30) |
| study93 |
1996–97 |
||
| Pneumonia and influenza deaths | |||
| Retrospective cohort | 1980–81 to | High | 33 (−7 to 58) |
| study84 | 1988–89 | ||
| Case control study87 |
1982–83 |
Elderly |
64 (19 to 84) |
| 1985–86 | 54 (7 to 77) | ||
| All-cause mortality | |||
| Retrospective cohort study94 | 1989–90 | Elderly | 75 (21 to 92) |
| Retrospective cohort | 1990–91 to | Elderly | 50 (44 to 56) |
| study85 | 1995–96 | ||
| Retrospective cohort | 1996–97 | Elderly | 60 (55 to 65) |
| study86 | 1997–98 | 39 (33 to 44) | |