Clinical effectiveness of 13-valent and 23-valent pneumococcal vaccination in middle-aged and older adults: The EPIVAC cohort study, 2015-2016.

Background: Clinical benefits using the 23-valent pneumococcal polysaccharide vaccine (PPsV23) or the 13-valent pneumococcal conjugate vaccine (PCV13) in adults are controversial. This study investigated clinical effectiveness for both PPsV23 and PCV13 in preventing pneumonia among middle-aged and older adults.

Methods: Population-based cohort study involving 2,025,730 persons ≥50 years in Catalonia, Spain, who were prospectively followed between 01/01/2015 and 31/12/2016. Primary outcomes were hospitalisation from pneumococcal or all-cause pneumonia and main explanatory variable was PCV13/PPsV23 vaccination status. Multivariable Cox regression models were used to estimate vaccination effectiveness adjusted for age and baseline-risk conditions.

Results: Cohort members were followed for 3,897,151 person-years (17,496 PCV13 vaccinated and 1,551,502 PPsV23 vaccinated), observing 3259 pneumococcal pneumonias (63 in PCV13 vaccinated, 2243 in PPsV23 vaccinated) and 24,079 all-cause pneumonias (566 in PCV13 vaccinated, 17,508 in PPsV23 vaccinated). Global incidence rates (per 100,000 person-years) were 83.6 for pneumococcal pneumonia (360.1 in PCV13 vaccinated, 144.6 in PPsV23 vaccinated) and 617.9 for all-cause pneumonia (3235.0 in PCV13 vaccinated, 1128.5 in PPsV23 vaccinated). In the multivariable analyses, the PCV13 appeared significantly associated with an increased risk of pneumococcal pneumonia (hazard ratio [HR]: 1.52; 95% confidence interval [CI]: 1.17-1.97; p = 0.002) and all-cause pneumonia (HR: 1.76; 95% CI: 1.61-1.92; p < 0.001) whereas the PPsV23 did not alter the risk of pneumococcal pneumonia (HR: 1.08; 95% CI: 0.98-1.19; p = 0.132) and slightly increased the risk of all-cause pneumonia (HR: 1.17; 95% CI: 1.13-1.21; p < 0.001). In stratified analyses focused on specific target population subgroups (i.e., elderly people, at-risk and high-risk individuals), protective effects of vaccination did not emerge either.

Conclusion: Data does not support clinical benefits from pneumococcal vaccination (nor PCV13 neither PPsV23) against pneumonia among Catalonian adults in the current era of universal PCV's childhood immunisation.