Effect of childhood pneumococcal conjugate vaccination on invasive disease in older adults of 10 European countries: implications for adult vaccination.

Background: Pneumococcal conjugate vaccines (PCVs) have the potential to prevent pneumococcal disease through direct and indirect protection. This multicentre European study estimated the indirect effects of 5-year childhood PCV10 and/or PCV13 programmes on invasive pneumococcal disease (IPD) in older adults across 13 sites in 10 European countries, to support decision-making on pneumococcal vaccination policies.
Methods: For each site we calculated IPD incidence rate ratios (IRR) in people aged ≥65 years by serotype for each PCV10/13 year (2011-2015) compared with 2009 (pre-PCV10/13). We calculated pooled IRR and 95% CI using random-effects meta-analysis and PCV10/13 effect as (1 - IRR)*100.
Results: After five PCV10/13 years, the incidence of IPD caused by all types, PCV7 and additional PCV13 serotypes declined 9% (95% CI -4% to 19%), 77% (95% CI 67% to 84%) and 38% (95% CI 19% to 53%), respectively, while the incidence of non-PCV13 serotypes increased 63% (95% CI 39% to 91%). The incidence of serotypes included in PCV13 and not in PCV10 decreased 37% (95% CI 22% to 50%) in six PCV13 sites and increased by 50% (95% CI -8% to 146%) in the four sites using PCV10 (alone or with PCV13). In 2015, PCV13 serotypes represented 20-29% and 32-53% of IPD cases in PCV13 and PCV10 sites, respectively.
Conclusion: Overall IPD incidence in older adults decreased moderately after five childhood PCV10/13 years in 13 European sites. Large declines in PCV10/13 serotype IPD, due to the indirect effect of childhood vaccination, were countered by increases in non-PCV13 IPD, but these declines varied according to the childhood vaccine used. Decision-making on pneumococcal vaccination for older adults must consider the indirect effects of childhood PCV programmes. Sustained monitoring of IPD epidemiology is imperative.
Competing Interests: Competing interests: The following authors report funding for research projects, travels or consultancy outside the submitted work: H-CS (project sponsored by Pfizer); ZH (travel grant from Pfizer), SNL (research including GSK, Pfizer, Sanofi Pasteur on behalf of St George’s University of London and Public Health England (PHE)); NKF (employed by PHE Respiratory and Vaccine Preventable Bacteria Reference Unit and PHE Immunisation that provided serotype surveillance reports to Affinivax, Pfizer and GSK); HR-K and JJ (employed by the National Institute for Health and Welfare that received research funding from GSK for the conduct of a trial of PCV10); AvdE (Pfizer grant for an investigator initiated project, consultancy fees from GSK, participation in the Pfizer Scientific Advisory board); CM-A (fees from GSK and grants from Pfizer); EV (Pfizer grants and personal fees); MC (Pfizer grants and personal fees); HH (research funding from Pfizer and Astellas).
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