Association Between Introduction of the 23-valent Pneumococcal Polysaccharide Vaccine (PPSV23) and Pneumonia Incidence and Mortality Among General Older Population in Japan: A Community-Based Study

Background With global aging, especially in Asia, preventing pneumonia among seniors is vital. The necessity of introducing pneumococcal vaccines among the elderly has been highlighted but there is a paucity of community-based real-world evidence on their effect. Sera Town in Hiroshima Prefecture, a superaged community, launched a distinctive pneumococcal vaccination support project for elderly residents and conducted a 5-year follow-up survey. This study evaluates the effectiveness of this vaccination initiative. Methods From October 2010 to March 2015, Sera Town recruited elderly residents for PPSV23 vaccination with partial cost subsidies. Participants were surveyed annually for five years post-vaccination to assess pneumonia incidence, calculated on a person-years basis. Using vital statistics from 2000 to 2016, we quantified changes in mortality rates associated with the vaccination support project through interrupted time series analysis. Results Of approximately 7,900 residents aged 65 and older, 3,422 (43%) participated in the project (median age: 84 years; range: 70-114 years; 56.7% female). Over 14,559 person-years of observation, 295 participants developed pneumonia. The post-vaccination incidence rate was 20.3 per 1,000 personyears (95% CI: 18.0-22.7). Interrupted time series analysis indicated a 25% reduction in Sera Town's pneumonia mortality rate post-project, reversing an annual increase of 0.23 per 1,000 population preproject to an annual decrease of 0.04 per 1,000 population post-project. Conclusion This study provided real-world evidence on the association with PPSV23 vaccination on the general elderly through a community-based study. The results may be particularly useful for regions where PPSV23 serotypes are prevalent, offering insights for areas facing aging challenges.