Large-scale resurgence of herpangina in Japan, following the easing of COVID-19 measures.

ABSTRACT

Objectives: This study examined the rise in herpangina cases and its demographic trends in Japan post-easing of COVID-19 restrictions in the summer of 2023, assessing its potential strain on pediatric healthcare. Methods: Weekly herpangina cases data from the National Institute of Infectious Diseases from 2017 to 2023 were analyzed using difference-in-differences methodology and Poisson regression models, incorporating variables such as time, the COVID-19 pandemic, and the easing of measures. Statistical significance was set at a two-sided P-value of 0.05. Results: A significant increase in herpangina cases was observed from the 19th to the 27th week of 2023, with a notable shift in age distribution compared to that of pre-pandemic years. Poisson regression analysis revealed a positive correlation between the number of herpangina cases and the easing of infection control measures. There was an increase in other respiratory illnesses, including respiratory syncytial virus, particularly in children aged 3 and above. Conclusion: We found a surge in herpangina cases in Japan after the easing of the COVID-19 restrictions during the summer of 2023, along with a noticeable increase in other respiratory illnesses, emphasizing the potential strain on pediatric healthcare and reinforcing the ongoing significance of implementing general infection prevention strategies.