Background: Elderly individuals are at high risk for pneumococcal pneumonia, and vaccination is crucial for prevention. This study aims to evaluate the effectiveness of the 23-valent pneumococcal polysaccharide vaccine (PPV23) in elderly individuals aged 65–84 years in Changshu City, identify key target groups, and explore potential factors influencing vaccine effectiveness. Methods: A multilevel cluster sampling method was employed to survey 2310 elderly individuals aged 65–84 years from four randomly selected towns/streets in Changshu City. Data were collected through face-to-face questionnaires and integrated with the immunization records system and electronic health records. Chi-square tests and multivariable logistic regression models were used to assess the association between PPV23 vaccination and pneumonia risk, with adjustments for potential confounding factors. Results: PPV23 vaccination significantly reduced the risk of pneumonia (adjusted OR = 0.69, 95% CI = 0.50–0.94, p = 0.019). The protective effect was more pronounced in individuals aged 75–79 years (OR = 0.56, 95% CI = 0.32–0.95) and females (OR = 0.48, 95% CI = 0.28–0.79). Chronic respiratory disease, survey location, gender, and age were identified as independent factors influencing vaccine effectiveness. Conclusions: PPV23 vaccination is effective in reducing pneumonia risk among elderly adults, particularly in specific subgroups. Future vaccination strategies should prioritize targeted programs for high-risk groups to improve coverage and effectiveness.
Zhang et al. (Sat,) studied this question.