ABSTRACT Rotavirus gastroenteritis decreased substantially worldwide during the COVID‐19 pandemic, and activity remained minimal in Hokkaido Prefecture, Japan, for 5 years after 2020. Hospital‐based surveillance in Hokkaido since July 2019 identified the first resurgence of rotavirus gastroenteritis in 2025. We analyzed temporal trends, age distribution, and viral genotypes among hospitalized children to characterize this resurgence. Over the full observation period (July 2019–Oct 2025), 113 hospitalizations were recorded, with 49 cases occurring between January and October 2025 after near‐absence from 2020 to 2024. Whole‐genome sequencing revealed dominance of equine‐like G3P8 and G8P8 strains closely related to contemporary international lineages and genetically distinct from strains previously detected locally. A marked shift in age distribution was evident: children aged 0–1 years accounted for 40.9% of cases before routine vaccination introduction (July 2019–Sep 2020), but none in 2025, whereas hospitalizations among children aged 7–12 years increased from 13.6% to 51.0%. These findings suggest that infants remained well protected by vaccination, but reduced circulation during the pandemic and waning immunity in older children enabled viral re‐emergence. Sustained genomic and epidemiological surveillance will be critical to monitor rotavirus evolution and inform vaccine impact in the post‐pandemic era.
Fukuda et al. (Fri,) studied this question.