薬理と治療

Abstract

Streptococcus pneumoniae is a leading cause of community–acquired pneumonia and invasive pneumococcal disease, with particularly high incidence and severity among older adults. More than 10 years have passed since Japan introduced routine adult vaccination with the 23–valent pneumococcal polysaccharide vaccine(PPSV23)in 2014. In 2024, the 20–valent pneumococcal conjugate vaccine(PCV20), which elicits stronger immune responses than capsular polysaccharide antigen alone, was approved. Subsequently, in October 2025, the Health Sciences Councilʼs Immunization and Vaccine Sectorial Committee approved the introduction of PCV20 as the successor to PPSV23 in the routine pneumococcal vaccination program for older adults. Meanwhile, recent adult vaccination rate remains around 40%, and raising this rate has become an important public health issue. Improving the vaccination rate will require not only greater disease awareness but also broader health economic considerations, including cost–effectiveness of vaccination and municipal vaccination subsidies. This article reviews the epidemiology of pneumococcal infections in adults, the evolution of adult pneumococcal vaccines, and evidence from health economic evaluations.(Jpn Pharmacol Ther 2026;54:107‒19)