Human metapneumovirus: an emerging public health threat and harbinger of a new pandemic.

Human metapneumovirus (hMPV), first identified in 2001, has increasingly been recognized as a significant cause of acute respiratory tract infections worldwide. Although often overshadowed by respiratory syncytial virus (RSV) and influenza, hMPV contributes substantially to the global burden of respiratory disease, particularly among young children, older adults, and immunocompromised populations. The COVID-19 pandemic further altered the epidemiology of respiratory viruses, disrupting established seasonal patterns and creating immunity gaps that have fueled unusual hMPV outbreaks in recent years. Despite its clinical relevance, hMPV remains underdiagnosed due to limited awareness, restricted access to reliable diagnostic tools, and frequent co-infections that obscure its contribution to disease severity. Currently, no licensed antivirals or vaccines exist, leaving supportive care as the only treatment option. Ongoing research into monoclonal antibodies, vaccine candidates, and combined RSV-hMPV preventive strategies offers promise but remains in early stages. In the context of global interconnectedness and the demonstrated capacity of respiratory viruses to cause widespread disruption, hMPV raises important concerns as a potential emerging public health threat. While unlikely to cause pandemic-scale disruption, hMPV's endemic circulation and disproportionate impact on vulnerable populations warrant its recognition as an emerging threat demanding proactive public health intervention and sustained investment in prevention strategies. This review examines hMPV's evolving role as a public health threat in the post-COVID-19 landscape, where altered epidemiological patterns and increased surveillance have highlighted its underappreciated impact.