Human Metapneumovirus Circulation and Seasonality on a Global Scale, 2016–2025: Changes in Patterns and Epidemic Timing in the Pre‐ Versus Post‐COVID‐19 Era

BACKGROUND: Human metapneumovirus (hMPV) circulates globally, yet its seasonal dynamics remain incompletely defined. Here, we describe the global timing, amplitude and duration of hMPV outbreaks, comparing the pre- versus post-COVID-19 periods. METHODS: Surveillance data for hMPV were retrieved from WHO FluNet from Week 1/2016 until Week 26/2025. We examined the epidemic peak timing, amplitude and duration across seasons and latitudes and compared patterns in 2016-2019 with those in 2021-2025. RESULTS: Over the study period, approximately 145,000 hMPV detections were reported to the WHO FluNet database from a total of 54 countries worldwide. Among the 15 countries with sufficient data to analyse seasonality, the epidemic timing aligned with geographic latitude, with the peak occurring in June-September in the Southern Hemisphere, February-April in the Northern Hemisphere, while the timing was variable across the intertropical belt. The amplitude of the peak varied across countries, with some countries characterized by single, well-defined peaks and others with more widespread epidemics throughout the season. The median epidemic duration was 19.5 weeks (range 15-36). After the appearance of SARS-CoV-2, marked shifts in timing and amplitude were observed, with delays or dislocations in several countries compared with pre-pandemic seasons. CONCLUSIONS: In this analysis of global surveillance data for hMPV (extended until June 2025), we highlighted latitudinal gradients in hMPV circulation, with disruptions associated with COVID-19. Our findings emphasize the importance of sustained, type-specific global surveillance to inform public health strategies and to characterize the post-COVID-19 global seasonality patterns of hMPV.