Human infections with swine-origin influenza A variant viruses have been reported sporadically worldwide, usually following direct or indirect exposure to pigs or contaminated environments.
Earlier this year, China has reported two human cases according to a World Health Organization report:
On 20 March 2026, China notified WHO of a laboratory-confirmed case of A(H1N1)v influenza virus infection in a child from Yunnan province. The patient had onset of illness on 30 January 2026, was hospitalized on 2 February with pneumonia, and recovered in a few days. The patient had reported exposure to domestic pigs prior to illness onset.
On 3 February 2026, China notified WHO of a laboratory-confirmed case of A(H1N2)v influenza virus infection in a child from Yunnan province. The patient had onset of mild illness on 20 January 2026, and the infection was laboratory-confirmed on 2 February 2026. The patient had reported exposure to domestic pigs prior to illness onset. This case and the one above are not epidemiologically linked.
Swine influenza viruses tend to result in mild clinical illness in most cases of human infection.
Influenza: What is the H and what is the N?
No sustained human-to-human transmission was identified associated with the events described above. Current evidence suggests that contemporary swine influenza viruses have not acquired the ability of sustained transmission among humans, therefore sustained human-to-human transmission is thus currently considered unlikely.