The resurgent threat: human metapneumovirus in a post-pandemic landscape.

The COVID-19 pandemic profoundly disrupted global respiratory virus transmission. Widespread nonpharmaceutical interventions (NPIs) sharply suppressed common pathogens, including human metapneumovirus (HMPV). However, as these measures were lifted, HMPV re-emerged with unexpected intensity-a resurgence driven primarily by population-wide "immunity debt" accrued during years of reduced viral exposure. Unlike influenza or RSV, HMPV's post-pandemic behavior has challenged long-held assumptions about seasonal respiratory virus dynamics. Traditional late-winter peaks have given way to out-of-season surges, year-round co-circulation with other viruses has become commonplace, and existing surveillance systems designed for a pre-pandemic world have proven inadequate. This review examines HMPV's renewed clinical and public health significance, focusing on epidemiological shifts, health system pressures, diagnostic gaps, and the critical need for coordinated, multi-pathogen preparedness. We argue that HMPV is no longer a minor seasonal pathogen but a persistent stressor requiring targeted countermeasures, including accelerated vaccine development, integrated surveillance, and healthcare system redesign.