Pneumococcal polysaccharide vaccine is recommended in western countries for individuals at high risk of pneumococcal illness. We undertook a systematic review of randomised controlled trials of pneumococcal vaccine in adults, to determine the effects on clinical outcomes.
Results: In industrialised populations, no benefit was detected for outcomes other than pneumococcal bacteraemia, and this did not reach statistical significance. In non-industrial populations, clear benefit was demonstrated for mortality and all-cause pneumonia.
Conclusion: Benefit from pneumococcal vaccination depends on the baseline risk of infection and characteristics of a given population. Evidence from randomised trials for widespread adult vaccination in industrial countries is lacking.