Japan's invasive meningococcal cases fell to one during COVID-19, then rebounded to 68 in 2025
Japan's national surveillance from January 2017 to October 2025 identified 288 IMD cases across pre-pandemic, pandemic and reopening phases. Cases fell from 48 in 2019 to one in 2021, then rose to 66 in 2024 and 68 by October 2025. Older adults consistently accounted for the most cases, adolescents clearly rebounded, and Tokyo rose more than Osaka/Kansai. No Expo-specific surge appeared. Cases and inbound travel had Spearman rho 1.000, although most infections were domestically acquired.