Clinical and epidemiological characteristics of human metapneumovirus in children in Hangzhou, China

This study aims to describe the epidemiology and genotypic diversity of human metapneumovirus (HMPV) in hospitalized children with pneumonia in Hangzhou, Zhejiang, China. From February 2022 to January 2023, nasopharyngeal swabs from hospitalized children with acute respiratory tract infections (ARTIs) in the Children's Hospital, Zhejiang University School of Medicine (Zhejiang, Hangzhou) were collected and tested for HMPV. Clinical characteristics and genotypes were analyzed on HMPV-positive samples. 3.43% (357/12993) of pediatric patients were HMPV-positive, and 287 of them were hospitalized with HMPV-induced pneumonia. 185 were classified as non-severe pneumonia group, and 102 as severe pneumonia group. Neutrophil to lymphocyte ratio (NLR), C-reactive protein to prealbumin ratio (CPAR) and C-reactive protein (CRP) were substantially higher in severe groups compared to non-severe groups across all patient categories (P < 0.05). There were 14 cases of B1 lineage infection, 7 cases of B2 lineage infection and 105 cases of A2.2.2 lineage infection in hospitalized patients. Under the prevention and control of the COVID-19 pandemic, the HMPV infection rate in pediatric patients with ARTIs has decreased, and the main lineage of HMPV infection in Hangzhou was A2.2.2. NLR and CPAR have higher predictive potential in severe patients.