Novel Influenza A Virus
Two human infections with novel influenza A viruses were reported by the Minnesota Department of Health. The patients were each infected with an influenza A(H3N2) variant (A(H3N2)v) virus.

Both patients are <18 years of age, sought healthcare during the week ending September 7, 2024 (Week 36), were not hospitalized, and have recovered from their illnesses. An investigation by state public health officials found that both patients, who are not contacts with one another, attended the same agricultural fair prior to their illness onset, where the first child had indirect swine contact and the second child had direct swine contact.

During the investigation into the first patient, public health officials identified a separate, and likely unrelated illness had occurred in the household. The day after attending the agricultural fair, all household members developed symptoms. One household member of the first patient was tested and was positive for SARS-CoV-2. All household members, including the case, recovered from their illness. Subsequently, the case patient developed new symptoms and tested positive for influenza A, which was further identified as A(H3N2)v. Other household members remained well. During the investigation into the second case, no illness was identified among contacts. No human-to-human transmission of influenza A(H3N2)v associated with either case was identified.

Including these reports, nine variant influenza virus cases have been reported during the 2023-2024 season (four A(H1N2)v, four A(H3N2)v, and one A(H1N1)v virus).

When an influenza virus that normally circulates in swine (but not people) is detected in a person, it is called a "variant" influenza virus. Most human infections with variant influenza viruses occur following exposure to swine, but human-to-human transmission can occur. It is important to note that in most cases, variant influenza viruses have not shown the ability to spread easily and sustainably from person to person.

Fourteen cases of human infection with influenza A (H5) virus have also been reported in the United States during the 2023-2024 season, for a total of 23 novel influenza A virus cases reported this season. Four of these influenza A (H5) virus infections occurred in individuals working with dairy cows, nine in individuals associated with poultry depopulation and disposal, and one in an individual with an unknown source of exposure. An ongoing outbreak of H5N1 continues in domestic dairy cows and poultry, and monitoring for additional human cases is ongoing.

Additional information on influenza in swine, variant influenza virus infection in humans, and guidance to interact safely with swine can be found at Swine Flu.