Fact Sheet: Protect Yourself Against H3N2v and Seasonal Influenza (Flu)

Background

Twelve human infections with a variant influenza A H3N2 virus (“H3N2v”) have been detected in 5 states of the country since August 2011 (Indiana, Iowa, Maine, Pennsylvania, and West Virginia). These are viruses that do not usually infect people but that occur in pigs and that are very different from human seasonal H3N2 viruses. In addition, regular flu viruses are spreading in the United States.

About half of the recent infections with H3N2v have occurred after contact with pigs, but in some cases, the virus seems to have spread from person-to-person. So far spread has not continued beyond one or two people. The symptoms and severity of H3N2v illness have been similar to seasonal flu.

This virus is related to human flu viruses from the 1990s, so adults should have some immunity, but young children probably do not. Early steps to make a vaccine against H3N2v have been taken, but no decision to mass produce such a vaccine has been made. Public health authorities are watching closely.

For more information, please visit the CDC Seasonal Influenza (Flu) website, and Information on H3N2 Variant Influenza A Viruses.

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Take Action

The risk of infection and spread – for H3N2v and seasonal flu viruses – can be reduced by taking a combination of actions. CDC recommends:

• Get a seasonal flu vaccine to protect yourself against seasonal flu viruses. (The seasonal vaccine is not designed to protect against H3N2v. Limited studies show that it may boost immunity against this virus in adults, but will probably not offer protection for children.)
• Take everyday preventive actions, including:
  • Cover your nose and mouth with a tissue when you cough or sneeze. (Throw the tissue in the trash after you use it.)
  • Wash your hands often with soap and water, especially after you cough or sneeze. If soap and water are not available, an alcohol-based hand rub may be used.
  • Avoid touching your eyes, nose or mouth. Germs spread that way.
  • Try to avoid close contact with sick people.
  • If you are sick, stay home from work or school until your illness is over.
• If you live in an area where H3N2v cases have been identified recently and develop flu like illness, contact your health care provider (a doctor, physician’s assistant, nurse practitioner, etc.). Tell them if you have had contact with pigs or with other sick people.
• If you live in an area where no H3N2v has been detected, follow CDC’s regular recommendations for seeking treatment for influenza. (If seeking treatment is recommended, and you have had contact with pigs, tell your health care provider about it.)
• Also, whenever you have flu symptoms and are seeing a health care provider, always remember to tell them if you have asthma, diabetes, heart disease, are pregnant, or are older than 65 or younger than 5 years. These conditions and age factors (and others) put you at high risk of serious complications if you get the flu.
• Flu symptoms usually include fever and respiratory symptoms, such as cough and runny nose, and possibly other symptoms, such as body aches, nausea, or vomiting or diarrhea.
• Health care providers will determine whether influenza testing and possible treatment are needed.
• There are influenza antiviral drugs that can be used to treat infection with H3N2v viruses as well as seasonal influenza viruses. More information about influenza antiviral drugs is available at Treatment (Antiviral Drugs).

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