Novel and Variant Influenza A Viruses

(Influenza A H3Nx, H5Nx, H6Nx, H7Nx, H9Nx, H10Nx)

A new (novel) influenza A virus is an influenza virus that causes human infection but is different from seasonal human influenza A viruses that circulate among people each year. This means that few people will have immunity to novel influenza A viruses, and a vaccine might not be widely available.

Some novel influenza A viruses are more concerning to public health officials because they have caused rare but serious disease or death and have been able to spread in a limited manner from person-to-person. Novel influenza A viruses are worrisome because they have the potential to cause a pandemic if the virus were to change and become easily and sustainably spread from person-to-person.

On this page:
Novel Avian Influenza A (H5N1, H5N2, H7N3, and H7N9)
      Where do avian influenza A viruses come from?
      How sick can people get?
      About an influenza pandemic
      Preventing novel avian influenza A infections and pandemics
Highly Pathogenic Avian Influenza Viruses
      What is highly pathogenic avian influenza (HPAI)?
      How is HPAI spread?
      Can humans be infected with HPAI?
Current Highly Pathogenic Avian Influenza A(H5N1) Outbreak
      What is the current HPAI Influenza A(H5N1) situation?
      How can I protect myself from HPAI Influenza A(H5N1)?
More information and resources

Novel Avian Influenza A (H5N1, H5N2, H7N3, and H7N9)

Where do avian influenza A viruses come from?

• Novel avian influenza A viruses usually come from animal influenza viruses. They do not normally infect humans, but sporadic human infections have occurred. Several subtypes of avian influenza A viruses are known to have infected people (H5, H6, H7, H9, H10 viruses).
  • More information on avian influenza A subtypes is available at CDC: Avian Influenza Type A Viruses.
• These viruses naturally live in wild waterfowl, such as ducks or geese, and wild aquatic birds, like loons, but usually don’t make them sick. However, these animals can spread avian influenza to other animals, including domestic animals, and sometimes to people.
• Influenza A viruses are constantly changing, which can lead to novel avian influenza A viruses circulating in domestic poultry, cattle, or other animals that can put people who interact with those animals at risk of infection.

How sick can people get?

• How sick a person becomes when infected will depend on the characteristics of the virus, whether or not the person has any immunity to that virus, and the health and age of the infected person. Most people have mild symptoms such as eye infection or a runny nose, but severe disease and death have been reported.

About an influenza pandemic

• An influenza pandemic is a global outbreak of a new influenza virus that is different from current and recently circulating human seasonal influenza viruses. It is possible, though rare, for non-human influenza A viruses to change enough to begin infecting people more easily and then begin spreading person-to-person. Novel avian influenza A viruses have the potential to cause a pandemic if the virus were to change to become easily and sustainably spread from person-to-person.

Preventing novel avian influenza A infections and pandemics.

• Public health workers all over the world closely watch trends in influenza infections through global disease surveillance. They also follow-up on occupational exposures to avian influenza A in people that have close contact with infected animals, such as farm workers, fair exhibitors, and veterinary staff. By closely monitoring individuals with exposures to animal influenza viruses, people can be treated faster to help prevent the spread of infection and the development of severe disease.

Highly Pathogenic Avian Influenza Viruses

What is highly pathogenic avian influenza (HPAI)?

• Avian influenza A viruses have two designations: low pathogenicity avian influenza (LPAI) and highly pathogenic avian influenza (HPAI). LPAIs cause mild or no signs of illness in poultry while HPAIs cause rapid death in domestic poultry such as chickens and turkeys. This designation does not refer to how likely the virus is to harm humans, other mammals, or other species of birds.

How is HPAI spread?

• Sick animals may be able to transmit influenza virus to people in their saliva, feces, milk, and other body fluids. Contaminated bedding, feed or water may also be a source of transmission from animals to humans. Human infections can occur when the virus is inhaled or gets into a person’s eyes, nose, or mouth.

Can people be infected with HPAI?

• Some HPAI viruses can infect people causing mild to severe respiratory illness or, rarely, death.
• Symptoms in infected people can include influenza-like illness (e.g., fever with cough and/or sore throat) and red, itchy eyes. Less common signs and symptoms include diarrhea, nausea, vomiting, or seizures.
• Person-to-person transmission of avian influenza viruses is very rare.
• HPAI is considered low risk to the general public, but there is an occupational risk for those who handle and care for infected animals; including agricultural workers, veterinarians, animal health responders and those who work with wildlife or potentially infected animals.
• For more information on the current Influenza A(H5N1), please visit Current Avian Influenza A(H5N1) Outbreak | Novel Flu For Health Professionals (including HPAI H5N1)

Current Highly Pathogenic Avian Influenza A(H5N1) Outbreak

What is the current HPAI Influenza A(H5N1) situation?

• Since 2022, the avian influenza A(H5N1) virus Clade 2.3.4.4b has been associated with outbreaks in wild birds, domestic poultry, and, more recently, dairy cattle, and other wild and domesticated animals, such as cats.
• Sporadic human infections have occurred in people who have had direct contact with infected birds, dairy cattle, or other animals.
• Public health and animal health officials are closely watching the situation. You can find the most current information on the HPAI response in Minnesota by visiting the Minnesota Board of Animal Health’s HPAI Dashboard.

• For more information on the current Influenza A(H5N1), please visit Current Avian Influenza A(H5N1) Outbreak | Novel Flu For Health Professionals (including HPAI H5N1)

How can I protect myself from HPAI Influenza A(H5N1)?

• Influenza A(H5N1) virus is considered low risk to the public, but there is a greater risk for those who handle and care for infected animals.
• Personal protective equipment (PPE) should be worn when working with animals that are suspected or confirmed to be infected with Influenza A(H5N1)
• PPE should include:
  • Washable or disposable long-sleeved coveralls or dedicated chore clothes than can be machine washed.
  • Rubber boots that can be disinfected or disposable plastic boots (replace if torn).
  • Washable or disposable head covering (some Tyvek coveralls have an attached hood).
  • Latex or nitrile gloves, but you may use cotton gloves underneath (replace if torn).
  • Goggles.
  • N95 respirator (mask) -- If an N95 is not available, use a KN95 or KF94 or surgical mask.
• Appropriate PPE depends on the hazards present and a site-specific risk assessment. If you have questions on the type of PPE to use or how to fit it properly, ask your employer.
• Personal protective equipment (PPE) is available to workers in industries who may have exposure to influenza A(H5N1) to help protect from the spread of HPAI.
  • Read the full letter to Minnesota workers in the dairy, poultry, milk processing, poultry and beef slaughter industries and learn how to request your PPE.
    • May 17, 2024, Letter to workers in the dairy, poultry, milk processing, poultry and beef slaughter industries (PDF)
• The Minnesota Department of Health (MDH) will reach out to any workers with known exposures to infected animals to do a short interview about your interactions with ill animals and to answer any questions you may have.
  • If you develop symptoms and you agree to it, MDH will help arrange for you to be tested.
  • Contact MDH at 651-201-5414 and ask for the Zoonotic Diseases Unit for questions on human health risk from avian influenza and how to protect yourself.
• Consider seasonal influenza vaccination if you have not yet received it this season (since August of 2023). While the seasonal influenza vaccine will not prevent avian strains of influenza, it can prevent illness due to seasonal influenza strains, which are still circulating.
  • Find where to get vaccinated with the vaccination finder: Where to Get Vaccinated
• Please see MDH human health sheets (link to human health sheet) for more information and specific recommendations

More information and resources

• General Resources
  • Minnesota Board of Animal Health’s HPAI Dashboard
  • CDC: H5N1 Bird Flu: Current Situation
  • 2022–2024 Detections of Highly Pathogenic Avian Influenza (usda.gov)
• Resources for workers in industries who may have exposure to influenza A(H5N1)
  • Dairy and Poultry Workers Personal Protective Equipment Video (Youtube)
  • Stay Healthy - Personal Protective Equipment Information for Dairy and Poultry Workers
  • Stay Healthy - Personal Protective Equipment Information for Dairy and Poultry Workers (Spanish)
  • Influenza A(H5N1) Infection in Companion Animals (PDF)
  • Upper Midwest Agricultural Safety and Health Center (UMASH) toolkit
  • CDC: Reducing Risk for People Working with or Exposed to Animal
• Variant Influenza A (H3N2v, H1N2v, H1N1v)
  Variant influenza A viruses do not usually infect people and are very different from human seasonal viruses. Influenza viruses that normally circulate in pigs are called “variant” viruses when they are found in people.
  Variant Flu For Exhibition Managers (Fairs and Shows) | Variant Flu For Health Professionals