Why Japan saw a major pertussis surge in 2025 while other countries peaked earlier

This study found that pertussis cases fell across Japan, Australia, New Zealand, China, and the USA during COVID-19 restrictions, then resurged afterward, with most countries peaking in 2024 but Japan showing a delayed major outbreak in 2025. In Japan, the surge was concentrated in school-aged children and adolescents, highlighting possible gaps in booster protection and the need to reassess immunization strategies.