Variant Influenza A
(H3N2v, H1N2v, H1N1v)

Influenza viruses that normally circulate in pigs are called “variant” viruses when they are found in people. Variant influenza A viruses do not usually infect people, and are very different from human seasonal influenza.

On this page:
Background
Symptoms
Transmission
Minimizing your risk
If you get sick
More information

Background

• Pigs are commonly infected with swine influenza viruses that are usually different from human influenza viruses.
• While rare, influenza can spread from pigs to people and from people to pigs.
• Influenza viruses that normally circulate in pigs are called “variant” viruses when they are found in people.
  • Variant influenza A H3N2 virus ("H3N2v") does not usually infect people but occurs in pigs, and is very different from human seasonal H3N2 viruses. A number of human infections with H3N2v have been detected in the United States since August 2011.
  • Similarly, the variant influenza A H1N2 ("H1N2v") virus strain is different from the human seasonal H1N2 virus. H1N2v is also different from the H3N2v strain.

Symptoms

• In general, the severity of illnesses associated with variant influenza have been similar to seasonal Influenza (Flu).

Transmission

• Most commonly, human infections with variant influenza A occur in people with direct or indirect exposure to infected pigs.
• To date there is no sustained human-to-human transmission of H3N2v or H1N2v. However, influenza viruses have the capacity to change and it's possible that this virus may become widespread.
• H3N2v and H1N2v are not transmissible by eating properly handled and prepared pork (pig meat) or other products derived from pigs.

Minimizing Your Risk

You can help prevent spread of influenza and other viruses:

• Never eat, drink or put things in your mouth in animal areas.
  • Don’t take food or drink into animal areas.
  • Never take toys, pacifiers, spill-proof cups, baby bottles, strollers or similar items into animal areas.
  • Avoid touching your eyes, nose or mouth.
• Persons at high risk for influenza complications should avoid swine exposure.
  • Persons at high risk include children younger than 5 years, people 65 years or older, pregnant women, and people with certain chronic medical conditions (like asthma, diabetes, heart disease, weakened immune systems, and neurological or neurodevelopmental conditions).
• Avoid close contact with pigs that look or act ill.
  • Watch your pigs for signs of illness and call a veterinarian if you suspect they might be sick.
• Avoid contact with pigs if you are experiencing flu-like symptoms.
  • Avoid contact for 7 days after symptoms begin or until you have been fever-free for 24 hours without the use of fever-reducing medications, whichever is longer.
• If you must come in contact with pigs while you are sick, or if you must come in contact with pigs known or suspected to be infected, or their environment, you should use appropriate protective measures.
  • Wear protective equipment (clothing, gloves, masks that cover your mouth and nose, and other personal protective equipment) and practice good respiratory and hand hygiene.
• Always cover coughs and sneezes.
• Wash your hands frequently with soap and running water before and after exposure to animals.
  • If soap and water are not available, use an alcohol-based hand rub.
  • Always wash hands thoroughly after contact with farm animals, pets, animal feces, and animal environments.
  • Hand Hygiene: more information on hand washing.

If You Get Sick

If you have flu symptoms, follow regular recommendations for seeking treatment for influenza.

• If you go to a doctor for flu symptoms following direct or close contact with swine, tell your doctor about this exposure.
• If you are at greater risk of serious flu-related complications, it's best to contact your doctor as soon as possible.
• Health care providers will determine whether influenza testing and possible treatment are needed.
  • Your doctor may prescribe antiviral drugs that can treat the flu, including Variant Influenza A. These drugs work better for treatment the sooner they are started. If you are prescribed antiviral drugs by your doctor, you should finish all of the medication, according to your doctor's instructions.

More about variant influenza A viruses

• CDC: Information on Swine/Variant Influenza
• Information for Exhibition Managers on Minimizing Influenza Transmission at Fairs and Swine Shows
• Information for Health Professionals on Influenza A Variant Viruses