Effectiveness of the 23-valent pneumococcal polysaccharide vaccine against community-acquired pneumonia in the general population aged ≥ 60 years: 3 years of follow-up in the CAPAMIS study.

ABSTRACT

BACKGROUND: The benefits of using the 23-valent pneumococcal polysaccharide vaccine (PPV23) are controversial. This study assessed clinical effectiveness of PPV23 in preventing community-acquired pneumonia (CAP) among the general population aged ≥ 60 years. METHODS: This was a population-based cohort study involving 27 204 individuals aged ≥ 60 years in Tarragona, Spain, who were prospectively followed from 1 December 2008 until 30 November 2011. Primary outcomes were hospitalization for pneumococcal CAP (bacteremic and nonbacteremic cases) and all-cause CAP. All CAP cases were radiographically confirmed and validated by checking clinical records. Cox regression was used to evaluate the association between pneumococcal vaccination and the risk of each outcome. RESULTS: Cohort members were followed for a total of 76 033 person-years (29 065 person-years for vaccinated subjects). Incidence rates (per 1000 person-years) were 0.21 for bacteremic pneumococcal CAP (0.14 vs 0.26 among vaccinated and unvaccinated subjects, respectively), 1.45 for nonbacteremic pneumococcal CAP (1.46 vs 1.44), and 7.51 for all-cause CAP (7.19 vs 7.71). In primary analyses including all cohort members, PPV23 did not appear to be effective against any analyzed outcome. However, a beneficial effect emerged in sensitive and stratified analyses. After multivariable adjustments, as compared with those never vaccinated, recent vaccination with PPV23 (<5 years ago) was associated with reduced risks of bacteremic pneumococcal CAP (hazard ratio [HR], 0.38; 95% confidence interval [CI], .09-1.68), nonbacteremic pneumococcal CAP (HR, 0.52; 95% CI, .29-.92), overall pneumococcal CAP (HR, 0.49; 95% CI, .29-.84), and all-cause CAP (HR, 0.75; 95% CI, .58-.98). CONCLUSIONS: Our data support a protective effect of recent PPV23 vaccination (within previous 5 years) against both pneumococcal and all-cause CAP.