Indirect impact of childhood 13-valent pneumococcal conjugate vaccine (PCV13) in Canadian older adults: a Canadian Immunization Research Network (CIRN) retrospective observational study.

Background: 13-valent pneumococcal conjugate vaccine (PCV13) has been part of publicly funded childhood immunisation programmes in Ontario and British Columbia (BC) since 2010. We assessed the indirect impact of infant PCV13 programmes on invasive pneumococcal disease (IPD) and all-cause pneumonia hospitalisation in older adults (aged ≥65 years) using a retrospective observational study.
Methods: We extracted monthly IPD and all-cause pneumonia cases from laboratory and health administrative databases between January 2005 and December 2018. Using a quasi-experimental difference-in-differences design, we calculated the ratio of risk ratios (RRRs) using incidence rates of IPD or all-cause pneumonia cases before (pre-PCV13 period) and after (PCV13 period) 2010 with rates of fractures as controls.
Results: The rates of all IPD or PCV serotype-specific IPD for older adults in both Ontario and BC did not change in 8 years after childhood PCV13 programme implementation. All-cause pneumonia increased in Ontario (RRR 1.38, 95% CI 1.11 to 1.71) but remained unchanged in BC.
Conclusions: Indirect community protection of older adults from hospitalisation with pneumococcal disease stalled despite maturation of childhood PCV13 vaccination programmes in two Canadian provinces.
Competing Interests: Competing interests: The Centre for Vaccine Preventable Diseases is operated by the Dalla Lana School of Public Health, which receives funding from government, philanthropic, not-for-profit and private sector organisation, including vaccine manufacturers. This includes a donation from Merck to the institution that supported the salary of SAF from April 2020 to February 2023. SAF does not receive funding directly from Merck or any personal payment or direct funds from vaccine manufacturers to support her research. Other authors declare no conflicts of interest. MS has been an investigator on projects funded by GlaxoSmithKline, Merck, Moderna, Pfizer, Sanofi-Pasteur, Seqirus, Symvivo and VBI Vaccines. All funds have been paid to his institute, and he has not received any personal payments.
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