Friday, August 05, 2022

CDC FluView Week 30: Novel Swine Variant Case In W. Virginia


As I reported yesterday in West Virginia DHHR Investigating Presumptive Swine Variant (H3N2v) Illness At County Fair, there are reports that several people in close contact with swine at the Jackson County fair have reported flu-like illness, and that both pigs and at least one human have tested positive for H3N2v (variant) influenza. 

Today's weekly FluView report contains a short report on this case, and the investigation. I'll have a brief postscript after the break. 

Novel Influenza A Virus

One human infection with a novel influenza A virus was reported by West Virginia. The patient was infected with an influenza A(H3N2) variant (A(H3N2)v) virus. The patient is a child < 18 years, was not hospitalized, and is recovering from their illness. An investigation by health officials showed that the patient participated in an agricultural fair and had direct contact with swine and that swine at this fair tested presumptively positive for influenza A. There have been additional reports of respiratory illness among people who attended the same fair; further investigation is ongoing. No person-to-person spread of this virus has been identified to date in this case.

When an influenza virus that normally circulates in swine (but not people) is detected in a person, it is called a “variant influenza virus.” These infections are relatively rare but happen sporadically. This is the first influenza A(H3N2)v virus identified in the United States during 2022.

Early identification and investigation of human infections with novel influenza A viruses are critical so that the risk of infection can be understood and appropriate public health measures can be taken. Additional information on influenza in swine, variant influenza virus infection in humans, and guidance to interact safely with swine can be found at Additional information regarding human infections with novel influenza A viruses can be found at

While it is rare that swine-variant infections spread efficiently in humans, it can happen, as we saw with the 2009 H1N1 pandemic.  The CDC currently lists  3 North American swine viruses as having at least some pandemic potential (2 added in 2019). 

H1N2 variant [A/California/62/2018]  Jul   2019   5.8  5.7 Moderate
H3N2 variant [A/Ohio/13/2017]          Jul   2019   6.6  5.8 Moderate
H3N2 variant [A/Indiana/08/2011]      Dec 2012   6.0  4.5 Moderate 

According to local media reports (see Pig barn will be off limits at State Fair following swine flu case in Jackson County), the public will be excluded from the swine exhibits at the state fair, which begins next week. 

A short while ago the West Virginia Dept of Agriculture tweeted the following confirmation of at least 6 pigs testing positive for swine influenza. 

We'll have to see whether other state and country fairs report similar findings in the weeks ahead.