Pathogenesis and current advancement in treatment and prevention strategies for Human metapneumovirus.

Human metapneumovirus (HMPV) is a well-identified paramyxovirus that has emerged as a significant global health threat, particularly following recent outbreaks in 2024-2025. It preferentially infects the respiratory epithelium and affects infants, the elderly, and immunocompromised populations. The clinical manifestations of the HMPV range from mild upper respiratory symptoms to severe diffuse bronchopneumonia. As of late 2024 and early 2025, HMPV has been responsible for 6.2% of positive respiratory illness tests and 5.4% of respiratory-associated hospitalizations in China, surpassing COVID-19, rhinovirus, and adenovirus. HMPV is a non-segmented, negative-sense single-stranded RNA virus with a genome of about 13.3 kb, and it is genetically related to Orthopneumovirus, particularly respiratory syncytial virus (RSV). Its transmission occurs primarily within households, and the virus poses significant risks to vulnerable populations. Immunologic responses to HMPV infections are diverse, with limited lasting immunity, leading to frequent reinfections. Diagnosis is problematic due to overlapping clinical manifestations of the disease alongside other respiratory viruses like RSV and influenza. Presently, no vaccines or antiviral treatments are available for HMPV, though several vaccine candidates are under investigation, including mRNA-1653 and IVX-A12, which have shown promising results in Phase I and Phase II clinical trials. Recent advances in understanding HMPV's molecular biology and immune modulation have led to exploring new therapeutic strategies, including monoclonal antibodies, fusion inhibitors, and RNA interference-based therapies.