Serotype distribution from nationwide adult invasive pneumococcal disease (IPD) surveillance and a multicentre study of pneumococcal community-acquired pneumonia were combined with reported vaccine efficacy to compare PCV20 and PCV21 in Japanese adults aged 65 and over. Adult IPD incidence, which fell during the pandemic, had returned to 89% of pre-pandemic levels by 2025, and PCV20-non-PCV21 serotypes accounted for 8.5% of isolates in 2023–2025. At 40% coverage the estimated preventable pneumonia cases were 2,821 for PCV20 and 4,765 for PCV21, with preventable pneumonia cases some 80–90 times more numerous than preventable IPD cases.
Why it is interesting: Quantifies how much of the older-adult pneumococcal burden is non-invasive, and how serotype drift could reverse the ranking of the two conjugate vaccines.