Efficacy of pneumococcal polysaccharide vaccine in immunocompetent adults: a meta-analysis of randomized trials.

The use of pneumococcal polysaccharide vaccine (PPV) is low in some countries, maybe because of doubts regarding its efficacy. This meta-analysis aims at combining evidence from randomized trials of PPV assessing its efficacy in preventing Streptococcus pneumoniae related diseases in immunocompetent adults. In the fourteen trials totalling 48,837 patients retrieved, PPV prevents definite pneumococcal pneumonia by 71%, presumptive pneumococcal pneumonia by 40%, and mortality due to pneumonia by 32%, but not all-cause pneumonia or death. No preventive effect was seen in the subgroup of patients aged 55 years or more, possibly due to a lack of statistical power.