Avian influenza A (H5N1) virus infection

The primary means of containing highly pathogenic avian influenza (HPAI) A(H5N1) virus in communities and decreasing the risk to human health is through H5N1 poultry immunisation or prompt culling of poultry with suspected or confirmed HPAI A(H5N1) virus infection and disinfection of the contaminated environment.

The most effective way to prevent HPAI A(H5N1) virus infection in humans is to minimise exposure by avoiding direct or close contact with sick or dead poultry (or other animals) and their environment in HPAI A(H5N1) virus-affected countries.

• The World Health Organization (WHO) recommends:[106]World Health Organization. ​Practical interim guidance to reduce the risk of infection in people exposed to avian influenza viruses. Aug 2024 [internet publication]. https://www.who.int/publications/i/item/B09116

  • Avoiding contact with animals (including wild animals) that are sick or dead from unknown causes

  • Reporting sick or unexpectedly dead animals to local authorities or a veterinarian

  • Following good food safety and personal hygiene practices, particularly hand washing

  • Properly handling and cooking poultry meat, eggs, and other animal products

  • Only slaughtering healthy animals for human consumption

  • Avoiding consuming raw or unpasteurised milk

  • Seeking health care if feeling unwell and reporting any possible exposure to sick animals

  • Wearing appropriate personal protective equipment when in direct or indirect contact with infected (or potentially infected) animals or their environment (e.g., occupational exposure).

• The US Centers for Disease Control and Prevention (CDC) advises members of the public to:[111]Centers for Disease Control and Prevention. Highly pathogenic avian influenza A(H5N1) virus: interim recommendations for prevention, monitoring, and public health investigations. Dec 2024 [internet publication]. https://www.cdc.gov/bird-flu/prevention/hpai-interim-recommendations.html ​​

  • Avoid exposure to sick or dead animals. If this is not possible, avoid unprotected (not using respiratory and eye protection) exposures to sick or dead animals, including wild birds, poultry, other domesticated birds, and other wild or domesticated animals (including cows).

  • Avoid unprotected exposures to animal faeces, litter, or materials contaminated by birds or other animals with suspected or confirmed H5N1 virus infection.

  • Cook poultry, eggs, and beef to safe internal temperatures and only consume pasteurised milk and milk products.

• The CDC offers specific guidance for employers to reduce the risk of infection in people working with or exposed to animals, such as poultry and dairy farmers and workers, and veterinarians and their staff.

  • CDC: reducing exposure for workers to avian influenza A viruses Opens in new window

• For people raising poultry or exotic birds in HPAI A(H5N1) virus-affected countries, efforts should be made to keep such birds away from wild waterfowl or other wild birds and their faeces, and away from water sources that are shared by wild waterfowl. Personal protective equipment should also be worn at all times when working in a potentially infected environment.[112]UK Health Security Agency. Avian influenza: guidance and algorithms for managing incidents in birds. Jan 2025 [internet publication]. https://www.gov.uk/government/publications/avian-influenza-guidance-and-algorithms-for-managing-incidents-in-birds

Vaccines

• Influenza A(H5N1) vaccines have been found to be safe and immunogenic in people when adjuvant is used.[113]Prieto-Lara E, Llanos-Mendez A. Safety and immunogenicity of prepandemic H5N1 influenza vaccines: a systematic review of the literature. Vaccine. 2010 Jun 11;28(26):4328-34. http://www.ncbi.nlm.nih.gov/pubmed/20403350?tool=bestpractice.com [114]Vesikari T, Forstén A, Herbinger KH, et al. Safety and immunogenicity of an MF59(®)-adjuvanted A/H5N1 pre-pandemic influenza vaccine in adults and the elderly. Vaccine. 2012 Feb 8;30(7):1388-96. http://www.ncbi.nlm.nih.gov/pubmed/22192847?tool=bestpractice.com [115]Langley JM, Risi G, Caldwell M, et al. Dose-sparing H5N1 A/Indonesia/05/2005 pre-pandemic influenza vaccine in adults and elderly adults: a phase III, placebo-controlled, randomized study. J Infect Dis. 2011 Jun 15;203(12):1729-38. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3100510 http://www.ncbi.nlm.nih.gov/pubmed/21606531?tool=bestpractice.com

• Various H5N1 and H5N8 vaccines are licensed around the world, including Europe, the UK, and the US, for use in children and adults in pandemic situations.[116]World Health Organization. ​Considerations for use of avian influenza A(‎H5)‎ vaccines during the interpandemic and emergence periods: report of a WHO virtual scientific consultation, September 2024. Jun 2025 [internet publication]. https://www.who.int/publications/i/item/9789240111462 ​ The US has a national stockpile that includes H5 vaccines that could be used if the virus begins transmitting easily from person to person.[117]US Food and Drug Administration. Influenza virus vaccine, H5N1 (for national stockpile). Feb 2018 [internet publication]. https://www.fda.gov/BiologicsBloodVaccines/Vaccines/ApprovedProducts/ucm094044.htm

• Information on the development and availability status of candidate vaccines is available from the WHO. WHO: zoonotic influenza – candidate vaccine viruses and potency testing reagents Opens in new window

• Healthcare workers worldwide are recommended to receive an annual seasonal influenza vaccine to decrease their risk of seasonal influenza and also to reduce the potential for nosocomial transmission of seasonal influenza viruses in the healthcare setting. Preventing seasonal influenza among people exposed to or infected with HPAI A(H5N1) virus may also decrease the theoretical risk of human co-infection with seasonal influenza A viruses and HPAI A(H5N1) virus and of viral genetic re-assortment (an event that could lead to the emergence of a potential pandemic influenza virus strain). However, seasonal influenza vaccination does not provide any protection against human infection with HPAI A(H5N1) virus infection.

Standard personal protective measures (e.g., home isolation, respiratory etiquette, hand hygiene) are recommended to slow the spread of infection; however, additional measures may also be recommended during pandemics, including:[118]Qualls N, Levitt A, Kanade N, et al; CDC Community Mitigation Guidelines Work Group. Community mitigation guidelines to prevent pandemic influenza - United States, 2017. MMWR Recomm Rep. 2017 Apr 21;66(1):1-34. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5837128 http://www.ncbi.nlm.nih.gov/pubmed/28426646?tool=bestpractice.com

• Voluntary home quarantine

• Use of face masks by people who are ill (or who are well)

• School, university, or child-care facility closures

• Social distancing measures (e.g., workplaces, mass gatherings)

• Environmental surface cleaning measures.

Post-exposure prophylaxis

• Antiviral post-exposure prophylaxis may be recommended for close contacts.

• See Treatment algorithm.