Awareness and implementation of adult pneumococcal vaccination in Shimane Prefecture, Japan: Repeated cross-sectional surveys and analysis of vaccination trends

BACKGROUND: Streptococcus pneumoniae is the leading cause of community-acquired pneumonia and invasive pneumococcal diseases in older adults. Although pneumococcal vaccination is effective in preventing severe disease, adult vaccination recommendations have become increasingly complex with the introduction of multiple vaccine types and poor dissemination among healthcare professionals. METHODS: A questionnaire survey was conducted among medical institutions in Shimane Prefecture across three survey periods: early (2017), middle (2019), and late (2023). The survey assessed institutional characteristics, clinical specialties, awareness of pneumococcal vaccination-related knowledge, and vaccination practices. Multivariate logistic regression analysis evaluated the association between awareness and vaccination implementation. RESULTS: Response rates were 43.5%, 38.0%, and 36.8% in the early, middle, and late survey periods, respectively. In the late period, 80.1% of the institutions were aware that two classes of pneumococcal vaccines were recommended for older adults. The proportion was significantly lower than that observed in the middle period (p = 0.041). Awareness that PPSV23 can be administered as a routine vaccination even after prior PCV vaccination was limited (47.6%) and declined from the middle to the late period (p = 0.001). Multivariate analyses demonstrated that the awareness of pneumococcal vaccine types and the benefits of sequential vaccination were markedly associated with vaccination practices. CONCLUSIONS: The dissemination of accurate information on pneumococcal vaccine types and vaccination recommendations may contribute to improving vaccination coverage. Strengthening continuous education and awareness activities targeting a broad range of healthcare professionals is warranted.