Impact of the 13-Valent Pneumococcal Conjugate Vaccine Among Adults: A Systematic Review and Meta-analysis.

Background: A notable reduction of the pneumococcal disease burden among adults was observed after the introduction of a 7-valent pneumococcal conjugate vaccine (PCV7) in childhood immunization programs. In 2010, a 13-valent pneumococcal conjugate vaccine (PCV13) replaced PCV7 in many jurisdictions; a comparative assessment of PCV13's impact was missing. Our objective was to summarize the available data and assess the change in the incidence of invasive pneumococcal disease (IPD) in adults after the introduction of PCV13 in childhood immunization programs.

Methods: We conducted a systematic literature search from January 1946 to May 2017 of randomized, controlled trials and observational studies OBS reporting the incidence of IPD, non-invasive pneumococcal disease, hospitalizations, and mortality in adults for the periods before and after the introduction of PCV13. Incidence rate ratios (IRRs) were pooled across studies using restricted, maximum-likelihood, random-effects models.

Results: From 3306 records,we included 29 OBS studies and 2033961 cases. Significantly lower IPD rates were seen after PCV13 introduction in adults aged <65 years (IRR 0.78, 95% confidence interval [CI] 0.72-0.85) and those aged ≥65 years (IRR 0.86, 95% CI 0.81-0.91). Lower rates of IPD were seen with PCV7 (IRR 0.45, 95% CI 0.38-0.54) and PCV13 serotypes (IRR 0.60, 95% CI 0.54-0.68). A significantly higher IRR of 1.10 (95% CI 1.04-1.17) for non-vaccine serotypes was observed, especially among those aged 65 years and older (IRR 1.20, 95% CI 1.11-1.29).

Conclusions: PCV13 use in children had a moderate impact on reducing the overall and vaccine-type IPDs, but there was a significant increase in non-vaccine type IPDs among adults, especially in those over 65 years.