A Cochrane review included 12 studies with a total of 2 171 subjects. Compared with control, the vaccine group had a lower likelihood of developing community-acquired pneumonia (table ), NNT=21 (95% CI 15 to 74), but findings did not differ specifically for pneumococcal pneumonia (very few confirmed pneumococcal pneumonias). Acute exacerbations of COPD were reduced. There was no statistically significant effect for reduction in hospital admissions, all cause mortality, or death from cardiorespiratory causes (table ).
| Outcome | Relative effect (95% CI) | Risk with control | Risk with pneumococcal vaccine (95% CI) | No of participants (studies) Quality of evidence |
|---|---|---|---|---|
| Pneumonia, community acquired, Follow-up: 6 to 36 months | OR 0.62 (0.43 to 0.89) | 143 / 1000 | 94 / 1000 (67 to 129) | 1372 (6) Moderate |
| Death from cardiorespiratory causes, Follow-up: 24 to 48 months | OR 1.07 (0.69 to 1.66) | 98 / 1000 | 104 / 1000 (70 to 153) | 888 (3) Low |
| Hospital admission: any cause, Follow-up: range 6 to 12 months | OR 0.74 (0.32 to 1.74) | 86 / 1000 | 65 / 1000 (29 to 140) | 391 (3) Moderate |
| COPD exacerbation, Follow-up: range 6 to 24 months | OR 0.60 (0.39 to 0.93) | 608 / 1000 | 482 / 1000 (377 to 591) | 446 (4) Moderate |
Comment: The quality of evidence is downgraded imprecise results (limited study size for each comparison) and by limitations in study quality (unclear allocation concealment and blinding).