A RECENT outbreak of human metapneumovirus (hMPV) in Puducherry, India, has revealed the emergence of two new lineages, A2.2.1 and A2.2.2, further underscoring the evolving nature of this virus and its significant impact on paediatric respiratory health.
The study analysed nasal swabs collected between January 2021 and June 2024. Of the 4,519 samples, 113 tested positive for hMPV, with the highest positivity rate (9.6%) observed during an outbreak from November 2022 to March 2023. December and January were peak months, accounting for 6.3% of cases during the outbreak.
Infants under one year were the most affected, comprising 67% of cases, with many experiencing wheezing and 6.9% developing seizures. Genetic analysis of the virus identified two major genotypes, A and B. Notably, most samples (85.29%) belonged to genotype A’s A2.1 subcluster, while a smaller proportion represented the novel A2.2.1 and A2.2.2 lineages.
“This outbreak highlights both the burden of hMPV on young children and the virus’s ability to evolve rapidly, posing ongoing challenges for surveillance and treatment,” the researchers stated.
hMPV is a leading cause of acute respiratory infections in children under five years of age. The discovery of new lineages stresses the importance of continued monitoring, genetic analysis, and research to develop targeted treatments and preventative measures for this increasingly diverse virus.
Aleksandra Zurowska, EMJ
Reference
Devanathan N et al. Emerging lineages A2.2.1 and A2.2.2 of human metapneumovirus (hMPV) in pediatric respiratory infections: Insights from India. IJID Regions. 2025;14:100486.
