Introduction: Human infections with swine-origin influenza A(H1N2)v viruses have been reported sporadically worldwide, usually following direct or indirect exposure to pigs or contaminated environments. This report describes the first laboratory-confirmed human infection with influenza A(H1N2)v virus in China.

Methods: Following detection of a human infection with influenza A(H1N2)v virus through influenza-like illness surveillance in Yunnan Province in January 2026, an epidemiological investigation, close-contact tracing, animal and environmental sampling, and laboratory testing were conducted. Throat swab specimens were collected for real-time RT-PCR and whole-genome sequencing. Representative influenza virus sequences from the GISAID database were used for sequence comparison and phylogenetic analysis.

Results: A 2-year-old boy presented with fever, cough, and rhinorrhea, and recovered after antiviral, antibacterial, and supportive treatments. Whole-genome sequencing revealed the full-length sequences of all eight gene segments. The virus shared the highest nucleotide homology with swine-origin influenza viruses circulating in China, with nucleotide identities ranging from 95.17% to 98.53%, suggesting a reassortant swine-origin influenza A(H1N2)v virus. Epidemiological investigations revealed no clear history of direct contact with pigs or poultry, although the pigs and poultry were raised near the patient´s residence. A total of 47 environmental samples and 28 animal samples were collected during the field investigation. Low viral loads of influenza A virus were detected in some swine and environmental samples; however, full subtyping and sequencing could not be performed for some samples because of low viral loads. Thirty close contacts were traced, and none developed relevant symptoms. No secondary cases or evidence of sustained human-to-human transmission was identified.

Conclusion: This case suggests a sporadic zoonotic transmission event with limited public health risk.