H3N2v

H3N2v is a variant of H3N2 influenza virus that has recently infected some people in the United States. When this virus occurs in pigs, it is called “swine influenza.” The virus does not usually infect people or spread among people. It is very different from human seasonal H3N2 viruses.

• One confirmed H3N2v case was reported in Utah in April 2012.
• Twelve confirmed H3N2v cases have been found in five states (Indiana, Iowa, Maine, Pennsylvania, and West Virginia) between August and December of 2011. All of the 12 patients recovered from their illness.
• Symptoms of H3N2v are similar to seasonal flu symptoms.
• The virus is not spreading easily among people in the general community.

CDC and HHS recommend a seasonal flu vaccine to protect against influenza illness this season. A precautionary vaccine against H3N2v is in development and will likely be ready for clinical trials in the coming months.

Is H3N2v a threat?

The first human infection with the H3N2v virus in 2012 has been reported in a child in Utah. The child has fully recovered after seeking medical attention in late March. CDC has confirmed this virus is very similar to the 12 human cases of H3N2v reported between August and December of 2011.

Between August and December of 2011, 12 human cases of H3N2v were reported. The 12 cases occurred in five states (Indiana, Iowa, Maine, Pennsylvania, and West Virginia). Eleven cases were in children. Half of the cases had exposure to pigs before they got sick; the other half of the patients reported no recent exposure to pigs before they got sick. Three of the 12 patients were hospitalized, and all 12 patients fully recovered.

What are the symptoms of H3N2v flu?

So far, symptoms and severity of H3N2v are similar to the seasonal flu symptoms.

How does H3N2v spread?

H3N2v can spread to humans from infected pigs. In some cases, H3N2v also has spread between people. This happens in the same way that seasonal flu viruses spread—through close contact with sick people who may spread their infections through coughs or sneezes. Since the virus has not continued spreading beyond one or two people, it is considered less contagious among people than the seasonal flu.  

How can I avoid H3N2v flu?

The seasonal flu vaccine is your best protection against the flu this season. The seasonal flu vaccine may provide some protection against H3N2v for adults but not for children. You should also follow everyday steps to keep yourself healthy this flu season. In addition, avoid close contact with animals, especially with pigs, that look or act sick. If you must come in contact with sick animals, you should take appropriate precautions such as wearing gloves.

A precautionary vaccine against H3N2v is in development and will likely be ready for clinical trials in the coming months.

What should I do if I think I have H3N2v?

If you live in an area where H3N2v cases have been identified recently and develop flu symptoms, contact your health care provider (doctor, physician’s assistant, etc…). Tell them if you have had contact with pigs or with other sick people. Your health care provider will determine whether influenza testing and possibly treatment are needed. Influenza antiviral drugs can treat H3N2v infection, just as they can treat seasonal flu infection.

Who monitors H3N2v in the United States?

The Centers for Disease Control and Prevention (CDC) tracks cases of H3N2v in humans. The CDC reports H3N2v cases in its flu surveillance report. The CDC also reports all human cases of H3N2v to the World Health Organization (WHO). The USDA is responsible for tracking flu in pigs.

Can people get swine influenza from eating pork?

Swine influenza has not been shown to be transmissible to people through eating properly handled and prepared pork (pig meat) or other products derived from pigs. For more information about the proper handling and preparation of pork, visit the USDA website fact sheet Fresh Pork from Farm to Table.

Related Links

Information on H3N2 Variant Influenza A Viruses

First H3N2 Variant Virus Infection Reported For 2012

Update: Influenza A (H3N2)v Transmission and Guidelines – Five States, 2011 (January 6, 2012)

Prevention Strategies for Seasonal and Influenza A(H3N2)v in Health Care Settings