Protective effect of pneumococcal vaccine against death by pneumonia in elderly subjects.

The present study assessed the effectiveness of the 23-valent pneumococcal polysaccharide vaccine to prevent pneumonia and death in older adults in a first-time report between January and December 2002. A prospective cohort study was conducted including all individuals>or=65 yrs of age assigned to one of eight primary care centres in Tarragona, Spain (n=11,241). The primary outcomes were community-acquired pneumonia (hospitalised or outpatient) and death from pneumonia. All pneumonias were validated by checking clinical records. The association between the pneumococcal vaccination and the risk of each outcome was evaluated by means of multivariate Cox proportional-hazard models, adjusted by age, sex, influenza vaccination status, comorbidity and immunological status. Pneumococcal vaccination did not alter the risk of hospitalisation from pneumonia (hazard ratio (HR): 0.80; 95% confidence interval (CI): 0.50-1.28) or overall pneumonia (HR: 0.86; 95% CI: 0.56-1.31), but the vaccine was associated with considerable reductions of death risk from pneumonia (HR: 0.28; 95% CI: 0.09-0.83). In conclusion, these results suggest that pneumococcal polysaccharide vaccine may not be effective in reducing the incidence of pneumonia, but may be able to diminish the severity of the infection. These findings support the effectiveness of the pneumococcal polysaccharide vaccine to prevent mortality caused by pneumonia in older adults, providing a new argument to recommend systematic vaccination in the elderly.