Introduction Despite the availability of publicly funded 23-valent polysaccharide pneumococcal vaccine (PPV23) for all adults aged 65 years and older, pneumococcal disease remains a public health concern in Ontario, Canada. Health Canada approved two new pneumococcal conjugate vaccines (PCV), 15-valent (PCV15) and 20-valent (PCV20) and we assessed their cost-effectiveness for older Ontarians.

Methods We conducted a cost-utility analysis using an individual-level state transition model to compare one dose of PCV (alone or in series with PPV23) with PPV23-only. We estimated sequential incremental cost-effectiveness ratio (ICER) expressed in costs (C$2022) per quality-adjusted life years (QALYs) from the healthcare payer perspective, discounted at 1.5% per annum. We performed sensitivity and scenario analyses to examine impact parameter uncertainties on the results.

Results A sequential comparison of vaccination strategies with no indirect effect from childhood vaccination resulted in an ICER of $44,324/QALY for PCV15-alone compared to PPV23-only, and $70,751/QALY for PCV20-alone versus PCV15-alone. None of the PCV15/20 combined with PPV23 programs were cost-effective at a cost-effectiveness threshold of C$50,000/QALY. PCV20 alone had an ICER of C$46,961/QALY compared to PPV23-only. When considering the indirect effects, use of PCV15/20 alone or in series with PPV23 were not cost-effective strategies. ICERs were mostly influenced by vaccine characteristics (effectiveness, waning, cost) and the incidence of pneumococcal community- acquired pneumonia.

Conclusion Vaccinating older adults with PCV15/20 is likely to reduce burden of pneumococcal disease and would be cost-effective initially, but is expected to be less economically attractive in the longer- term when herd immunity benefits from childhood vaccination programs are considered.

The authors have declared no competing interest.

This study was funded by a University of Toronto Connaught Global Challenge Award 2019/2020. GBG also received a postdoctoral fellowship award from the Center for Vaccine Preventable Diseases at the Dalla Lana School of Public Health. The Center for Vaccine Preventable Diseases receives funding from government, philanthropic, not-for-profit and private sector organizations, including vaccine manufacturers. This includes a donation from Sanofi to Center for Vaccine Preventable Diseases. A donation from Merck to the Center for Vaccine Preventable Diseases, at the Dalla Lana School of Public Health, 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. The funder had no role in study design, implementation, data analysis and interpretation. All authors attest they meet the ICMJE criteria for authorship. This research was also supported, in part, by a Canada Research Chair in Economics of Infectious Diseases held by Beate Sander (CRC 2022 00362).

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