Importation-Driven Measles Resurgence and the Fragility of Elimination, Japan, 2024–2026
Abstract
As measles elimination unravels across the Americas, Europe, and the Western Pacific, Japan is experiencing a resurgence of measles; the World Health Organization had verified elimination of measles in Japan in 2015. By epidemiologic week 20 of 2026, a total of 498 cases had been reported, exceeding every full-year total since 2020. Median case-patient age has fallen to 26 years, shifting the burden from a generation who received single-dose measles vaccinations to younger cohorts caught between successive vaccination-policy transitions. Among case-patients with a documented 2-dose vaccination history, more than half experienced modified measles, an attenuated, easily missed illness that delays diagnosis and isolation. As mass gatherings concentrate global travel, Japan has become a sentinel for the fragility of measles elimination, including in countries that consider elimination status secure. Surveillance shows importation-driven resurgence; the shift in genotype profile from D8 to B3 predominance back to D8 enabled tracking of source countries.
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BibTeX
@article{yuji2026importationdriven,
title = {{Importation-Driven Measles Resurgence and the Fragility of Elimination, Japan, 2024–2026}},
author = {Koichiro Yuji and Wakako Yuji and Eisuke Adachi},
journal = {Emerging Infectious Diseases},
year = {2026},
month = oct,
doi = {10.3201/eid3211.261187},
url = {https://doi.org/10.3201/eid3211.261187},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Importation-Driven Measles Resurgence and the Fragility of Elimination, Japan, 2024–2026
AU - Koichiro Yuji
AU - Wakako Yuji
AU - Eisuke Adachi
PY - 2026
DA - 2026/10/30
JO - Emerging Infectious Diseases
DO - 10.3201/eid3211.261187
UR - https://doi.org/10.3201/eid3211.261187
AB - As measles elimination unravels across the Americas, Europe, and the Western Pacific, Japan is experiencing a resurgence of measles; the World Health Organization had verified elimination of measles in Japan in 2015. By epidemiologic week 20 of 2026, a total of 498 cases had been reported, exceeding every full-year total since 2020. Median case-patient age has fallen to 26 years, shifting the burden from a generation who received single-dose measles vaccinations to younger cohorts caught between successive vaccination-policy transitions. Among case-patients with a documented 2-dose vaccination history, more than half experienced modified measles, an attenuated, easily missed illness that delays diagnosis and isolation. As mass gatherings concentrate global travel, Japan has become a sentinel for the fragility of measles elimination, including in countries that consider elimination status secure. Surveillance shows importation-driven resurgence; the shift in genotype profile from D8 to B3 predominance back to D8 enabled tracking of source countries.
SN - 1080-6040
SN - 1080-6059
ER -