Evaluating clinical effectiveness of pneumococcal vaccination in preventing stroke: the CAPAMIS Study, 3-year follow-up.

BACKGROUND: Cerebrovascular benefits using the 23-valent pneumococcal polysaccharide vaccine (PPV23) are controversial. This study assessed clinical effectiveness of PPV23 in preventing ischemic stroke in people older than 60 years. METHODS: We conducted a population-based cohort study involving 27,204 individuals of 60 years or older in Tarragona, Spain, who were prospectively followed from December 01, 2008, until November 30, 2011. Outcomes were neuroimaging-confirmed ischemic stroke, 30-day mortality from stroke, and all-cause death. Pneumococcal vaccination effectiveness was evaluated by Cox regression analyses, estimating hazard ratios (HRs) adjusted for age, sex, comorbidities, and influenza vaccine status. RESULTS: Cohort members were followed for a total of 76,033 person-years, of which 29,065 were for vaccinated subjects. Overall, 343 cases of stroke, 45 deaths from stroke, and 2465 all-cause deaths were observed. Pneumococcal vaccination did not alter the risk of stroke (multivariable HR: 1.04; 95% confidence interval [CI]: .83-1.30; P=.752), death from stroke (HR: 1.14; 95% CI: .61-2.13; P=.686), and all-cause death (HR: .97; 95% CI: .89-1.05; P=.448). In analyses focused on people with and without a history of cerebrovascular disease, the PPV23 did not emerge effective in preventing any analyzed event, but influenza vaccine emerged independently associated with a reduced risk of death from stroke (HR: .51; 95% CI: .28-.93; P=.029) and all-cause death (HR: .73; 95% CI: .67-.81; P<.001). CONCLUSIONS: Our data support that the PPV23 does not provide benefit against ischemic stroke, but it also supports a beneficial effect of influenza vaccine in reducing specific- and all-cause mortality risk in the general population older than 60 years.