Objective: This case report details the epidemiological characteristics of the first human case of swine-origin influenza A(H1N2)v infection identified in mainland China, to formulate guidelines for the prevention and control of human swine-origin influenza A (H1N2) virus infections.

Methods: Clinical and epidemiological data of the case were collected through field epidemiological investigation combined with laboratory testing. Specimens were collected from the patient, close contacts, animals subjects (including one deceased pig), and environmental matrices and analyzed to trace the potential infection source and characterize the clinical and epidemiological features.

Results: This study describes a sporadic, isolated case of human infection with swine influenza A(H1N2)v in mainland China, with no evidence of human-to-human transmission. Prior to symptom onset, the patient inhabited a high-risk mixed residential setting with frequent close exposure to domestic livestock and poultry. Specially, his townhouse stood adjacent to his great-uncle´s residence, where swine were raised; the great-uncle also documented the mortality of one pig. But had no contact with human confirmed cases presenting similar clinical manifestations. Testing of the collected specimens confirmed influenza N2 subtype positivity in lung tissue specimens obtained from the deceased pigs, whereas all remaining animal and environmental specimens yielded negative test results. The patient was eventually discharged after clinical recovery. A total of 30 close contacts completed self-health monitoring and throat swab screening. No influenza-like illness developed among these individuals throughout the monitoring period, and all throat swab specimens yielded negative test results. No secondary cases were detected during medical monitoring, and targeted environmental disinfection was implemented accordingly.

Conclusion: The likely source of infection for the reported case was identified as deceased pigs harboring N2-subtype influenza A virus. Therefore, enhanced surveillance of novel influenza subtypes such as A(H1N2)v and improved swine influenza vaccination are crucial for the targeted prevention and control of human infections by these emerging viruses.