Influenza A (H3N2) Variant Virus
Influenza viruses that normally circulate in pigs are called “variant” viruses when they are found in people. Influenza A H3N2 variant viruses (also known as “H3N2v” viruses) with the matrix (M) gene from the 2009 H1N1 pandemic virus were first detected in people in July 2011. The viruses were first identified in U.S. pigs in 2010. From July – December 2011, 12 cases of H3N2v infection were detected in the United States (Indiana, Iowa, Maine, Pennsylvania, and West Virginia). From January to September 2012, 307 cases of H3N2v infection across 11 states were detected. These infections were mostly associated with prolonged exposure to pigs at agricultural fairs. Limited human-to-human spread of this virus has been detected as well (Iowa, West Virginia) but no sustained community spread of H3N2v has been identified at this time. It's possible that sporadic infections and even localized outbreaks among people with this virus will continue to occur. The Centers for Disease Control and Prevention (CDC) continues to monitor this situation closely and will report cases of H3N2v and other variant influenza viruses weekly in FluView and on the case count tables on this website. CDC has developed guidance for the public to protect against H3N2v, and guidance for public health and health care workers.
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Basics
What is H3N2v, Who has Been Impacted, Prevention, Treatment…
Prevention
Protect Yourself, Take Action to Prevent the Spread, Fact Sheets…
Treatment
Drugs to Treat H3N2v, Stay Home When Sick, Caring for Someone Who is Sick…
News & Highlights
H3N2v Developments, Updates, Feature Stories, Spotlights…
Health Care Providers
CDC Health Advisory, Prevention Strategies, Diagnostic Testing…
Guidance for Public Health
Surveillance Guidance, Laboratory Testing Guidance…
Other Guidance
Interim Guidance for Fair Organizers and School Administrators…
Materials & Resources
Printable materials including Flyers and Posters, Webinars…
Outbreak Characterization
- Localized outbreaks
- Swine-to-human transmission; rare, limited human-to-human
- No sustained or community transmission
Info for Specific Audiences
What's New & Updated
Preventive Actions
CDC Recommendations For People At High Risk:
- If you are at high risk of serious flu complications and are going to a fair where pigs will be present, avoid pigs and swine barns at the fair this year. This includes children younger than 5 years, people 65 years and older, pregnant women, and people with certain long-term health conditions (like asthma, diabetes, heart disease, weakened immune systems, and neurological or neurodevelopmental conditions).
If you are not at high risk, take these precautions:
- Don’t take food or drink into pig areas; don’t eat, drink or put anything in your mouth in pig areas.
- Don’t take toys, pacifiers, cups, baby bottles, strollers, or similar items into pig areas.
- Wash your hands often with soap and running water before and after exposure to pigs. If soap and water are not available, use an alcohol-based hand rub.
- Avoid close contact with pigs that look or act ill.
- Take protective measures if you must come in contact with pigs that are known or suspected to be sick. This includes minimizing contact with pigs and wearing personal protective equipment like protective clothing, gloves and masks that cover your mouth and nose when contact is required.
- To further reduce the risk of infection, minimize contact with pigs and swine barns.
