Epidemiology of Kawasaki Disease After the COVID-19 Pandemic in Japan 2023-2024.
Kawasaki disease cases in Japan rebounded 45.5% in 2023 after pandemic-era decline.
Epidemiology of Kawasaki Disease After the COVID-19 Pandemic in Japan 2023-2024.
IMPORTANCE: The COVID-19 pandemic may serve as a natural experiment, with pandemic-associated changes in the epidemiology of Kawasaki disease (kawasaki disease) potentially informing understanding of kawasaki disease pathogenesis.
To assess long-term kawasaki disease incidence across 50 years and to examine pandemic-associated changes in kawasaki disease epidemiology across age groups.
DESIGN, SETTING, AND PARTICIPANTS: This cohort study was a descriptive epidemiologic analysis of data from the Japanese Nationwide Survey of Kawasaki Disease conducted from 2023 to 2024, along with 50 years of historical data.
The current survey registered 15 032 and 14 809 patients with kawasaki disease in 2023 and 2024, respectively (overall, 57.3% male; median [IQR] age, 2 [1-4] years).
Across the 50-year study period, despite the population under 5 years of age declining in Japan by 61.6%, kawasaki disease incidence rates increased 16.1-fold.
Indexed incidence rates (using 2017 as a baseline of 100) demonstrated that patients 5 to 9 years of age had the largest decline (nadir of 54.2 in 2021, 45.8% below baseline) and the largest rebound (134.8 in 2024, 34.8% above baseline).
In this nationwide cohort study of kawasaki disease in Japan, kawasaki disease incidence rebounded after the relaxation of COVID-19 pandemic-related restrictions, with age-dependent patterns.
Nonpharmaceutical interventions (eg, mask-wearing) during the pandemic may explain the greater rebound pattern observed in older children; however, the minimal changes in infants suggest different exposure pathways to potential kawasaki disease triggers.
These findings support an age-stratified approach to kawasaki disease pathogenesis research, distinguishing infants from older children.