Evaluating clinical effectiveness of 13-valent pneumococcal conjugate vaccination against pneumonia among middle-aged and older adults in Catalonia: results from the EPIVAC cohort study.

Background: Benefits using the 13-valent pneumococcal conjugate vaccine (PCV13) in adults are controversial. This study investigated clinical effectiveness of PCV13 vaccination in preventing hospitalisation from pneumonia among middle-aged and older adults.

Methods: Population-based cohort study involving 2,025,730 individuals ≥50 years in Catalonia, Spain, who were prospectively followed from 01/01/2015 to 31/12/2015. Primary outcomes were hospitalisation for pneumococcal or all-cause pneumonia and death from any cause. Cox regression models were used to evaluate the association between PCV13 vaccination and the risk of each outcome, adjusting for age, sex and major comorbidities/underlying risk conditions.

Results: Cohort members were observed for a total of 1,990,701 person-years, of which 6912 person-years were PCV13 vaccinated. Overall, crude incidence rates (per 100,000 person-years) were 82.8 (95% confidence interval [CI]: 77.7-88.1) for pneumococcal pneumonia, 637.9 (95% CI: 599.0-678.7) for all-cause pneumonia and 2367.2 (95% CI: 2222.8-2518.7) for all-cause death. After multivariable adjustments we found that the PCV13 vaccination did not alter significantly the risk of pneumococcal pneumonia (multivariable-adjusted hazard ratio [mHR]: 1.17; 95% CI: 0.75-1.83; p = 0.493) and all-cause death (mHR: 1.07; 95% CI: 0.97-1.18; p = 0.190), although it remained significantly associated with an increased risk of all-cause pneumonia (mHR: 1.69; 95% CI: 1.48-1.94; p < 0.001). In stratified analyses focused on middle-aged or elderly persons and immunocompromised or immunocompetent subjects, PCV13 vaccination did not appear effective either.

Conclusion: Our data does not support clinical benefits of PCV13 vaccination against pneumonia among adults in Catalonia. It must be closely monitored in future studies involving more vaccinated person-time at-observation.