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.