Efficacy of pneumococcal vaccination in adults: a meta-analysis
Anke Huss, PhD, Pippa Scott, MSc, Andreas E. Stuck, MD, Caroline Trotter, PhD and Matthias Egger, MD MSc
From the Institute of Social and Preventive Medicine (Huss, Scott, Egger), University of Bern, Bern, Switzerland; the Department of Geriatrics (Stuck), Inselspital University Hospital, Bern, Switzerland; the University Department of Geriatrics (Stuck), Spital Netz Bern Ziegler, Bern, Switzerland; and the Department of Social Medicine (Trotter, Egger), University of Bristol, Bristol, UK
Correspondence to: Dr. Matthias Egger, Institute of Social and Preventive Medicine, University of Bern, Finkenhubelweg 11, CH-3012 Bern, Switzerland; fax 41 31 631 35 20; firstname.lastname@example.org
Background: Clinical trials and meta-analyses have produced conflicting results of the efficacy of unconjugated pneumococcal polysaccharide vaccine in adults. We sought to evaluate the vaccine’s efficacy on clinical outcomes as well as the methodologic quality of the trials.
Methods: We searched several databases and all bibliographies of reviews and meta-analyses for clinical trials that compared pneumococcal polysaccharide vaccine with a control. We examined rates of pneumonia and death, taking the methodologic quality of the trials into consideration.
Results: We included 22 trials involving 101 507 participants: 11 trials reported on presumptive pneumococcal pneumonia, 19 on all-cause pneumonia and 12 on all-cause mortality. The current 23-valent vaccine was used in 8 trials. The relative risk (RR) was 0.64 (95% confidence interval [CI] 0.43–0.96) for presumptive pneumococcal pneumonia and 0.73 (95% CI 0.56–0.94) for all-cause pneumonia. There was significant heterogeneity between the trials reporting on presumptive pneumonia (I2 = 74%, p 0.05). The results for all-cause mortality in double-blind trials were similar to those in all trials combined. There was little evidence of vaccine protection among elderly patients or adults with chronic illness in analyses of all trials (RR 1.04, 95% CI 0.78–1.38, for presumptive pneumococcal pneumonia; 0.89, 95% CI 0.69–1.14, for all-cause pneumonia; and 1.00, 95% CI 0.87–1.14, for all-cause mortality).
Interpretation: Pneumococcal vaccination does not appear to be effective in preventing pneumonia, even in populations for whom the vaccine is currently recommended.