A cost-effectiveness analysis of revaccination and catch-up strategies with the 23-valent pneumococcal polysaccharide vaccine (PPV23) in older adults in Japan

Abstract

Objective: In Japan, the National Immunization Program (NIP) includes PPV23 as the primary vaccination for adults and catch-up cohorts. The Japanese Association for Infectious Diseases recommends revaccination for older adults who received primary vaccination ≥5 years earlier. The cost-effectiveness of adding revaccination and/or continuing catch-up vaccination in the NIP was evaluated from the public payer perspective in Japan.

Methods: The Markov model included five health states: no pneumococcal disease, invasive pneumococcal diseases (IPD), non-bacteremic pneumococcal pneumonia (NBPP), post-meningitis sequelae, and death. Cohorts of adults aged 65–95 were followed until age 100 or death: 2014 cohort (aged 65–95, vaccinated: 2014); 2019 cohort (aged 65: 2019); and 2019 catch-up cohort (aged 70–100: 2019, unvaccinated: 2014). Strategies included: (1) vaccinate 2014 and 2019 cohorts; (2) vaccinate 2014 and 2019 cohorts and revaccinate both; (3) strategy 1 and vaccinate 2019 catch-up cohort; (4) strategy 2 and vaccinate 2019 catch-up cohort; and (5) strategy 4 and revaccinate 2019 catch-up cohort. Parameters were retrieved from global and Japanese sources, costs and QALYs discounted at 2%, and incremental cost-effectiveness ratios (ICERs) estimated.

Results: Strategy 1 had the highest number of IPD and NBPP cases, and strategy 5 the lowest. Strategies 3–5 dominated strategy 1 and strategy 2 was cost-effective compared to strategy 1 (ICER: ¥1,622,153 per QALY gained). At a willingness-to-pay threshold of ¥5 million per QALY gained, strategy 2 was cost-effective and strategies 3–5 were cost-saving compared to strategy 1.

Conclusions: Strategies including revaccination, catch-up, or both were cost-effective or cost-saving in comparison to no revaccination and no catch-up. Results can inform future vaccine policies and programs in Japan.

Keywords:

• Pneumococcal pneumonia
• revaccination
• vaccination
• 23-valent pneumococcal polysaccharide vaccine (PPV23)
• cost-effectiveness
• Japan

JEL classification codes:

• I10
• I19

Transparency

Declaration of funding

This research was funded by Merck & Co., Inc., Kenilworth, NJ.

Declaration of financial/other relationships

XY and TP are employees of Merck & Co., Inc., Kenilworth, NJ. YJ is an employee of Merck Sharp & Dohme Ltd., Hoddesdon, Hertfordshire, UK. KT and MA are employees of MSD K.K, Tokyo, Japan. Peer reviewers on this manuscript have received an honorarium from JME for their review work. One reviewer discloses employment with Merck, while the remaining reviewers have no relevant financial relationships to disclose.

Acknowledgments

The authors thank Emily Farrington, Claire Spencer, and Yunni Yi, employees of Adelphi Values, for their assistance with manuscript preparation and submission.

Data availability statement

The data that support the findings of this study are available from the corresponding author, XY, upon reasonable request.