Authors: A. Bouma, H.A. Lim, T.J.D. van Riet, H.I.J. Roest

Since 2021, high pathogenicity of avian influenza virus H5N1 (HPAI H5N1) has spread worldwide.  It is present in many countries, causing widespread infections in poultry that are often controlled through large-scale culling. The virus is also established in wild bird populations and has led to infections in several mammal species. While human infections remain rare, the risk of a broader public health event, such as a pandemic, cannot be ignored. Reducing virus spread is therefore a priority for both animal and human health. Vaccination could be one of the tools to support this goal and should not be hampered by unjustified trade barriers.

Global situation of HPAI

HPAI H5N1 continues to cause recurring outbreaks in poultry and mammals, with often devastating impacts on the poultry sector and wild animal populations. Control measures rely largely on culling infected flocks, leading to the loss of millions of birds. This approach warrants reconsideration, particularly given the sustained circulation of the virus in wild bird populations. More sustainable, long-term strategies are needed, and vaccination could serve as a valuable additional tool to achieve this goal.

Vaccination, animal health and safe trade

In 2023, the WOAH World Assembly of Delegates adopted Resolution No. 28, recognising vaccination as a complementary disease control tool. WOAH international standards stipulate that vaccination use does not affect a country’s HPAI-free status, provided surveillance demonstrates the absence of infection.

Despite this progress, several challenges remain. Vaccination programmes are currently applied in only a limited number of at-risk countries. Although more countries are considering vaccination, concerns about vaccination and surveillance costs, product value and potential impacts on international trade continue to limit uptake, especially in exporting countries. While some trade barriers are justified, others appear disproportionate and need further discussion.

To address these challenges, the Netherlands set up an international working group on HPAI vaccination and trade. Together with Canada, the European Commission, France, the United Kingdom, the United States of America and WOAH, the Netherlands organised a meeting of this working group last January. Participants agreed to work together to make HPAI vaccination feasible in the near future, providing necessary assurances to allow safe trade.  

Key issues to be addressed

The working group underlined the need to develop and recognise minimum requirements that would facilitate international trade in products from vaccinated poultry and eliminate unjustified trade barriers. The group also noted that agreements with respect to vaccination and trade should be aligned with existing international standards, such as zoning, and should include appropriate surveillance and control measures that support virus control while maintaining trade confidence.

Next steps

A side event will be organised during the WOAH General Session in May. The international working group will present progress to date and outline planned activities. The focus will be on improving understanding of vaccination performance and exploring the development of minimum, widely supported surveillance programme requirements to demonstrate the absence of infection and facilitate trade in products from vaccinated poultry.

In addition, WOAH will develop guidelines for surveillance of HPAI in vaccinated poultry population, with the aim of supporting disease status recognition and safe trade.

Members interested in supporting future vaccination efforts are encouraged to express their interest.

Looking ahead

The goal is to move towards a more sustainable poultry sector that prioritises animal health and welfare, while also protecting public health and the environment.

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WOAH has launched the Guidelines Surveillance of High Pathogenicity Avian Influenza for Smallholder Poultry Systems in Resource-Limited Settings, providing Veterinary Authorities and Veterinary Services involved in high pathogenicity avian influenza(HPAI) surveillance, as well as wildlife, environmental and public health services, animal diagnostic laboratories and other One Health partners with practical recommendations to assist in designing surveillance programmes for the detection of HPAI virus in smallholder poultry systems (SHPS), tailored to the needs and contexts of resource-limited settings.

What the Guidelines Contain

The guidelines Section 1 showcases the diversity and complexity of SHPS beyond the value chain and highlights the importance of community participation to address issues associated with poultry health and enhance effective disease surveillance programmes in such settings.

Section 2 outlines the main objectives, target audience and the international framework, standards and existing tools that link to this guidance.

Section 3 provides six practical phases for developing a surveillance programme in a participative manner — from defining objectives and mapping poultry systems to choosing methods, setting up communication and reporting pathways, and evaluating performance.

Section 4 focuses on training, including a training of trainers model to strengthen local capacity.

The Annex contains ready-to-use tools, templates, figures and evaluation indicators to help users apply the guidance in the field.

Why Did WOAH Develop These Guidelines?

Low- and middle-income countries (LMIC) of the world face several challenges in preventing and responding to avian influenza outbreaks, particularly among smallholder (backyard) poultry farmers. Low-sensitivity surveillance systems in SHPS hinder early detection, thereby increasing the spread of the virus. Furthermore, conventional surveillance programmes often demand substantial and ongoing funding while lacking the flexibility to address the full range of disease surveillance needs in SHPS, particularly where resources are constrained.

In the 90th WOAH General Session in May 2023, following the animal health forum and technical item on avian influenza, Resolution No. 28 was adopted that include the recommendation to support poultry keepers, particularly small holders, in implementing correct usage of disease prevention and control tools, such as enhanced biosecurity, early identification of clinical signs and reporting, to prevent the introduction and spread of HPAI. It was identified as a need to provide Members with practical surveillance guidelines targeting small-scale poultry farmers (backyard), tailored to the local socio-economic context.

To this end, WOAH has published these practical guidelines tailored to local contexts, safeguarding farmers’ livelihoods and ensuring the stability of the poultry industry.

How Were the Guidelines Developed?

In 2025, WOAH launched a consultancy to develop these science-based guidelines. They were authored by experts from the Centre for Applied One Health Research and Policy Advice and Agriculture, Fisheries and Conservation Department, Hong Kong and the Institut National de Recherche pour l’agriculture, l’alimentation et l’environnement, France.

In April 2025, the first draft underwent peer review by a WOAH ad hoc Group, which provided expert opinions and recommendations while ensuring diverse and regional perspectives were considered. The WOAH Scientific Commission for Animal Diseases (SCAD) also reviewed the draft to confirm scientific soundness and alignment with WOAH international standards. Following these reviews and revisions, the guidelines were officially published on the WOAH website (English, French, Spanish) in January 2026.

WOAH encourages users of these guidelines to share their implementation experience and to provide constructive feedback through WOAH Delegates or their representatives, so that this publication can be further refined and adapted to the ever-changing ecology of HPAI viruses, food production systems and surveillance tools.

More information

Recording of the launch webinar on 25 February 2026: Launch of Guidelines on Surveillance of HPAI for Smallholder Poultry Systems in Resource-Limited Settings

Contact: Science and Disease Management Department ([email protected])

Updated on 8 May 2024

The ongoing spread of High Pathogenicity Avian Influenza (HPAI) in different regions of the world, alongside the recent detections of cases in cattle, is raising concerns within the international community.

While HPAI primarily affects poultry and wild birds, avian influenza can occasionally be transmitted to mammals, including humans. In the last two years, an increasing number of H5N1 avian influenza cases are being reported in terrestrial and aquatic mammalians animals.

The recently reported detections of HPAI in dairy cattle in the United States of America, have raised international concerns. Infected cattle may be asymptomatic or with mild illness showing non-specific clinical signs such as decreased milk production, thicker-colostrum‐like milk, reduced appetite, lethargy, fever and dehydration. These infections in cattle could indicate an increased risk of H5N1 viruses becoming better adapted to mammals, and potentially spilling over to humans and other livestock.  

Initial investigations so far have revealed that raw milk from infected cows is a high-risk material. Thus, only milk produced by healthy cows should be commercialised. There are evidence of horizontal virus transmission from infected lactating cows to other animals including cows, cats and poultry.  No specific adaptation of the virus to either humans or mammals was identified. Several studies are being carried out to further explore the pathogenesis and transmission routes of these viruses, including among cattle and from cattle to other animals. 

In collaboration with its Reference Centres, our networks of experts and Members, the World Organisation for Animal Health (WOAH) is closely monitoring the situation to assess the risks to animals, but also to humans, which is currently considered low. Timely and transparent reporting is crucial to maintain a good understanding of the disease situation and prevent any type of misinformation or disinformation. 

WOAH reminds its 183 Members that, based on the information currently available, restrictions to the international trade of healthy cattle and their products are not recommended unless justified by an import risk analysis conducted according to the WOAH Terrestrial Animal Health Code Chapter 2.1.  

WOAH calls on its Members to: 

• Maintain enhanced avian influenza SURVEILLANCE in domestic and wild birds.  
• INCLUDE HPAI as a differential diagnosis, in non-avian species, including cattle and other livestock populations, with high risk of exposure to HPAI viruses, in particular:  
  • Animals showing clinical signs compatible with avian influenza; 
  • Sick or dead domestic animals near affected premises;   
  • Suspected, including apparently healthy animals, that have been exposed to or epidemiologically linked to suspected or confirmed HPAI in birds or cattle (i.e. situated in HPAI high-risk areas or in areas where avian influenza has been confirmed).
• REPORT cases of HPAI in all animal species, including unusual hosts, to WOAH through its World Animal Health Information System (WAHIS). Genetic sequences of avian influenza viruses should be shared in publicly available databases. 
• CONSIDER poultry vaccination as complementary avian influenza control measure;  PREVENT the introduction and spread of the disease by implementing strict biosecurity measures in livestock holdings, in particular in milking parlour and EMPLOY good production and hygiene practices when handling animal products. Raw milk or raw milk products from HPAI infected cows or exposed to those infected with HPAI should not be used to feed animals or for human consumption.
• PROTECT  humans in close contact with or handling sick cattle or other sick livestock and their products. Exposed humans should always take precautionary measures to avoid getting infected and minimize the risk to mechanically carry the virus that could infect livestock or companion animals. This should include wearing personal protective equipment, avoiding visiting other livestock premises after the exposure and implementing standard food safety measures when handling animal products from exposed livestock.  
• AVOID implementing unjustified trade restrictions. Import risk management measures should be scientifically justified and in line with the WOAH International Standards.

Technical guidelines for the adaptation of diagnostic tests for Influenza A in animals including cattle and other species as well as different types of samples such as milk and nasal swabs are available in the OFFLU website and will be regularly updated.  

WOAH is fully committed to supporting its Members to mitigate the risks associated with avian influenza. We will continue to engage with our networks of experts, OFFLU,  as well as public and private partners, notably through the One Health Quadripartite and the Global Framework for Transboundary Animal Diseases (GF-TADs) to provide technical updates as more information becomes available.

Since 2005, avian influenza has had a staggering toll, with over 500 million birds lost to the disease worldwide [1]. Its devastating impact extends beyond domestic and wild birds, threatening livelihoods, food security and public health. The recent shift in the disease’s ecology and epidemiology has heightened global concern as it has spread to new geographical regions. It has also caused unusual die-offs in wild birds and led to an alarming increase in mammalian cases. The rapidly evolving nature of avian influenza and changes in its patterns of spread [2] require a review of existing prevention and control strategies. To effectively contain the disease, protect the economic sustainability of the poultry sector and reduce potential pandemic risks, all available tools must be reconsidered including vaccination.

The current spread of avian influenza is a major concern for the poultry industry, public health and biodiversity. Given recent developments in its epidemiology, and the increasing circulation of high pathogenicity avian influenza (HPAI) in wild animals, stricter biosecurity measures and mass culling of poultry may no longer be sufficient to control the disease. With the seasonal north-south migration of wild birds, countries must be prepared for an increase in outbreaks and should consider complementary approaches, such as vaccination, in line with existing international animal health and welfare standards [3]. 

Key facts

•  The epidemiology of avian influenza is evolving: the disease is gradually losing its seasonal nature, and high pathogenicity strains are circulating in wild birds. 
• This intensified circulation increases the likelihood of virus evolution and spillover to new species, including mammals, posing a risk to human health. 
• All available science-based disease control tools must be considered. In certain epidemiological contexts, vaccination can be an effective complement to other control strategies. 
• If properly implemented, vaccination should not be a barrier to safe trade. 
• Wider use of vaccination stimulates research innovation, improving the quality of available vaccines. 

Considering vaccination as part of available avian influenza control measures 

Traditionally, HPAI has been of concern mainly in domestic birds, with its control envisaged at farm level. Current transmission patterns show it is now circulating in wild bird populations, driving its spread not only across different farms, but also within farms. In practice, this has made it more and more difficult to protect a farm from disease introduction, due to increased exposure, both from neighbouring poultry farms and wild birds. 

There has been a global rise in HPAI outbreaks [4] and an increase in the genetic diversity of circulating virus strains. Thus, the use of sanitary control measures alone may no longer be a sustainable solution to effectively contain the disease. One such measure is the systematic mass culling of poultry, which results in heavy economic losses for farmers, has a lasting impact on their livelihoods and raises social, animal welfare and environmental concerns. Due to its negative impact on the sustainability of production practices and the image of the poultry industry to consumers, its acceptability must be scrutinised. 

Measures such as surveillance for early detection and monitoring of avian influenza viruses, preventive health measures (biosecurity) and disease control measures (culling, movement controls, quarantine) remain at the core of any avian influenza control strategy. 

However, poultry vaccination can no longer be excluded from the available alternatives and should be considered a complementary tool. When scientifically justified, it offers several advantages: 

• Prevention and control of outbreaks in vaccinated domestic bird populations resulting in reduced virus circulation within and between flocks and lower risk of spillover to wildlife. 
• Reduced economic losses, both direct (e.g. bird deaths) and indirect (e.g. mass culling and trade disruption). When properly implemented, avian influenza vaccination is compatible with safe trade, according to WOAH international standards. 
• Lower risk of human exposure to avian influenza viruses, and thus of a potential pandemic, in line with the One Health approach [5] . 
• Minimised environmental impact by reducing the risk of spill over to wild animals. 
• Incentives for innovative research to maintain the efficacy of vaccines over time, thanks to the experience gained. This encourages manufacturers to develop and improve access to effective and up-to-date vaccines. 

In certain socioeconomic contexts, vaccination against avian influenza can contribute to the overall sustainability of the poultry industry and to the preservation of outdoor production systems. These are often a cultural heritage, even though such systems are not optimal in their biosecurity. It helps to maintain the health of domestic and wild birds, ensuring a stable supply of poultry products for consumers and preserving biodiversity. In addition, vaccination programmes with pre-established risk-based protocols enhance a country’s outbreak preparedness, both in the speed of response and preparation for the increased risk. 

Responsibilities of countries opting for poultry vaccination 

Avian influenza vaccination should be considered as part of a broader disease prevention and control strategy. This must include other provisions, such as biosecurity measures, disease surveillance for early detection, rapid response to outbreaks and a well-planned exit strategy. Vaccination can be a temporary measure to better control the disease situation. National Veterinary Authorities [6] are charged with the decision to vaccinate based on a risk-evaluation, which depends on several factors and involves varied responsibilities, including: 

• The availability of high quality and reliable registered vaccines that meet WOAH international standards [7] and remain effective against circulating strains. Vaccine composition must be under constant review to respond to changing circumstances and epidemiology. 
• Sufficient surveillance capacity to demonstrate that vaccination does not interfere with virus monitoring and early detection of outbreaks in vaccinated and unvaccinated bird populations. Robust surveillance systems are essential to monitor the potential presence of avian influenza viruses in domestic and wild birds, as well as in mammals. This determines which strains are circulating and ensures that immunisation targets are met, and appropriate control measures are implemented. However, building and maintaining this capacity is resource-intensive and not possible in all countries. 
• The commitment of poultry producers to adhere to the disease control strategy in place. 
• Data collection from producers and veterinarians on the duration of protection provided by vaccination and the time of virus shedding after vaccination if live vaccines are used. Such data will help to better define vaccination strategies. 
• The capacity to ensure the traceability of the entire process, from vaccine production to on-farm administration and post-vaccination monitoring, including the traceability of vaccinated animals and their products. 

Vaccine selection, vaccination protocols and monitoring are critical components of a successful vaccination programme. The level of flock immunity required to prevent transmission hinges on several factors. Depending on the disease epidemiology, Veterinary Authorities – in consultation with the poultry sector – may decide to vaccinate only certain species in a selection of production systems [8].

Vaccination is compatible with the pursuit of safe trade in poultry and poultry products 

To date, despite the global crisis, vaccination has been used only in a limited number of countries as a preventive, emergency or systematic measure to protect poultry or other captive bird populations from HPAI. Concerns about international trade restrictions hamper its use, although the inclusion of vaccination as a control tool has been endorsed by international standards adopted by the World Assembly of WOAH national Delegates. 

Unjustified trade restrictions on poultry and poultry products from vaccinated flocks have a huge impact on a sector that contributes significantly to global food security and the economy. In fact, poultry meat exports account for 11% of total production, while egg exports account for 3% of production [9]. Imports of commercial genetic stocks of poultry are also essential to support meat and egg production systems of all countries. In addition, poultry meat and eggs are a low-cost, high-quality, low-fat protein food source, providing commodity redistribution and economic benefits and supporting the livelihoods of small-scale farmers. It is vital to maintain their international trade while ensuring the safety of these exchanges. This can be guaranteed in two ways: 

• Countries that vaccinate will need to provide appropriate certification to their trading partners to ensure that their measures comply with WOAH science-based international standards. They must also demonstrate their plans to carry out necessary surveillance of circulating strains once vaccination is in place, and their capacity to prove the absence of virus circulation. 
• Importing countries should make risk-based decisions and implement science-informed measures that allow for safe trade while preventing the spread of avian influenza. This is critical to avoid the closure of trade borders and the subsequent economic consequences for the poultry industry, farmers and consumers. 

In accordance with WOAH international standards, the use of vaccination does not affect the status of a country or zone as being HPAI-free if surveillance supports the absence of infection. Trade in poultry and poultry products can be conducted safely alongside vaccination. 

81% of WOAH Members (107/133 answers) did not use any sort of avian influenza vaccination in the past five years [10], whereas 112 countries and territories reported disease presence over this period [1].

Policy recommendations 

The use of vaccination in poultry against HPAI remains the decision of each national Veterinary Authority in consultation with poultry producers. It should be tailored to the specific epidemiological and socioeconomic context, and the needs and capacities of each country or region. 

Flexibility and adaptability are essential to effectively address the dynamic nature of the disease and its potential threat to domestic and wild bird populations, and to public health. Some key considerations for national policies are outlined hereafter. 

Decision-making 

As described in WOAH standards [6], the decision to vaccinate poultry must be: 

• part of a broader avian influenza control strategy with an exit plan; 
• accompanied by an solid monitoring and surveillance system for domestic and wild bird populations to guide the selection of appropriate vaccine strains; 
• based on the availability of sufficient financial, technical and human resources for disease surveillance and the maintenance of effective vaccination campaigns; 
• combined with the enforcement of relevant regulations, including licensing, quality control, and safety standards for vaccines. 

Monitoring and evaluation 

The maintenance of vaccinations should rely on the regular evaluation of vaccination programmes to gather evidence on their effectiveness and adjust them as necessary, based on surveillance data and scientific developments. 

International cooperation, including trade 

The implementation of avian influenza vaccination programmes requires a careful balance between disease control and maintenance of safe international trade. Prior to exchange, trading partners should: 

• establish mechanisms to ensure cooperation and transparent communication between relevant stakeholders, including ministries, Veterinary Authorities and producers; 
• engage in bilateral discussions to agree on certification requirements and trade protocols, and to address trade concerns, so mutual recognition can be ensured in peacetime. 

Ultimately, multilateral dialogue and adherence to WOAH standards are key to ensuring that if a country decides to introduce vaccination against avian influenza, it will be carried out appropriately, without sanitary risks and will not form an unnecessary barrier to safe trade. Efforts should be made to maintain open lines of communication, thus minimising trade disruption while protecting animal health and welfare, as well as human and environmental health. 

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