Epidemiological and Molecular Characterization of Human Metapneumovirus (HMPV) in Children Under 14 Years of Age in Shijiazhuang City, China.

Objective

The objectives of this study were to analyze the epidemiological characteristics and whole-genome features of human metapneumovirus (HMPV) among children under 14 years of age in Shijiazhuang during 2022-2025, enrich the whole-genome data of HMPV in China, and provide a basis for further understanding the genetic diversity of the virus and for its prevention, control, and transmission intervention.

Methods

A total of 1920 cases of acute respiratory infection were enrolled from three sentinel hospitals in Shijiazhuang. Nucleic acid screening was performed using real-time PCR. Whole-genome sequencing was conducted on 25 positive samples. Phylogenetic trees were constructed using the neighbor-joining method in MEGA, and nucleotide and amino acid sequence identity analyses were performed.

Results

The overall detection rate of HMPV from 2022 to 2025 was 4.17%. A prominent peak in winter 2024 was the major distinguishing feature. Temporally, both influenza-like illness (ILI) and severe acute respiratory infection (SARI) cases showed marked seasonality during 2022-2025, with high-incidence periods in December-March and April-June. BLAST alignment and phylogenetic analysis showed that among the 25 sequenced HMPV specimens, genotype B2 was the most frequently identified genotype (13/25, 52%).

Conclusions

HMPV epidemics in Shijiazhuang during 2022-2025 mainly occurred in winter-spring and spring-summer, with a notable detection peak in December 2024. The B2 genotype predominated among the sequenced HMPV isolates obtained in this study. The amino acid variation in the G gene was significantly higher than that in other genomic regions.