IntroductionSince the beginning of the winter season of 2024–2025, ARTI cases have increased and have further surpassed the baseline level in some countries in the temperate Northern Hemisphere. A notable increase in human metapneumovirus (hMPV) infections has been observed in northern provinces of China, resulting in widespread concern (https://www.who.int/emergencies/disease-outbreak-news/item/2025-DON550).HMPV, first identified in 2001, belongs to the Metapneumovirus genus within the family Pneumoviridae.1 It is considered a common respiratory virus responsible for the common cold, primarily affecting infants and children under five years of age. Annually, there are an estimated 14.2 and 0.0161 million hMPV-associated acute lower respiratory infection (ALRI) cases and deaths, respectively, among children younger than five years old.2 The clinical manifestations of hMPV infection are typically asymptomatic or mild in healthy adults, with symptoms such as cough, fever, sore throat, and runny nose.3 However, for high-risk populations, such as older people, immunocompromised individuals, and patients with underlying chronic conditions, hMPV infection can lead to severe clinical manifestations, such as pneumonia.4 Despite ongoing research and development, no approved antiviral drugs or licensed vaccines are currently available. Furthermore, hMPV is not routinely tested and monitored in many countries despite its substantial health burden, which is not conducive to global cooperation in response to infectious diseases.5,6HMPV can be divided into two major genotypes, A and B, which are further categorized into six subgenotypes, A1, A2a, A2b, A2c, B1, and B2, on the basis of the sequence variation of the attachment (G) and fusion (F) glycoproteins.7,8 HMPV variants with 180- or 111-nucleotide duplications (nt-dup) in the G protein-encoded gene of A2c, designated A2c180nt-dup and A2c111nt-dup strains, were first described in Japan in 2014 and Spain in 2017, respectively.9,10,11 A2c111nt-dup strains have been identified globally, such as in China, Croatia, and other countries, and are gradually becoming the dominant strains.12,13,14,15,16The rise in hMPV infection cases has prompted concerns regarding the potential involvement of novel variants, thereby underscoring the critical need for sustained and ongoing surveillance of respiratory pathogens. This approach can also satisfy the needs for early alerts regarding emerging respiratory diseases that have the potential to cause epidemics or pandemics.17,18 Limited data are available regarding epidemiological and genetic features of hMPV in patients of all age categories in Beijing, particularly in the postcoronavirus disease (COVID-19) era. The Beijing Respiratory Pathogen Surveillance System (RPSS), a year-round regional surveillance system comprising 35 sentinel hospitals initiated in 2014, aims to monitor the epidemics of ARTI-associated respiratory pathogens. Here, we used surveillance data from this system to characterize the epidemiological features and genetic diversity of hMPV in Beijing between 2014 and 2024.ResultsStudy populationBetween September 1, 2014, and December 31, 2024, a total of 79,793 patients diagnosed with ARTI were investigated and sampled, spanning ten complete seasons (the 2014–2015 season to the 2024–2025 season). Male patients accounted for 54.9% (418 patients lacked sex information), which was consistent with the demographic characteristics in China. The age of the participants ranged from less than one month to 109 years, with a median age of 38 years (IQR: 8–66 years; 1691 patients were missing age information).Among all included patients, hMPV was identified in 1245 patients (1.6%, 1245/79,793), and 514 (49.2%) patients were inpatients. With respect to clinical diagnoses, 460 (44.0%) patients had upper respiratory tract infections (URTI), 639 (61.1%) had non-severe community-acquired pneumonia (nsCAP), 97 (9.3%) had severe community-acquired pneumonia (sCAP), and 49 (4.7%) had other diseases (such as bronchitis and tonsillitis) (P