VLC voices: Vaccine stewardship of highly pathogenic avian influenza – insights from experts

Highly pathogenic avian influenza (HPAI) is caused by viruses that can mutate rapidly and affects wild and domestic birds, mammals like sea lions or cattle, and occasionally humans. Its spread poses a significant threat to poultry farming, food security and the livelihoods of millions of people, affecting poorer populations the most. While some countries have used vaccination to control the disease, others have yet to do so or need to improve their vaccination programmes for better prevention.

In this context, the FAO Virtual Learning Centers developed an online course,Vaccine stewardship in prevention and control of highly pathogenic avian influenza, which was piloted in Asia and the Pacific region between June and July 2024. This course aimed to provide countries with practical guidance on HPAI vaccination strategies, covering the twelve principles of avian influenza vaccination stewardship, decision-making on vaccination use, and how to implement effective vaccination programmes. Experts Leslie Sims and David E. Swayne, who contributed to the development of this course, share their insights on the role of vaccine stewardship to control HPAI.

What is vaccine stewardship? Can it benefit both endemic and avian influenza-free countries?

Many countries are expressing interest in using vaccination as an additional tool to help control and prevent HPAI. The concept of avian influenza vaccination stewardship was developed to help countries make decisions on whether vaccination can be of benefit and, if so, build appropriate vaccination programmes against HPAI that generate sustained high levels of immunity in the vaccinated population. If this cannot be achieved, there is a risk of infection occurring in vaccinated flocks and driving changes in the virus that allow it to resist the immunity produced.

The course also built on successful experiences with vaccination, such as programmes introduced to update vaccines when needed in China, Indonesia, Viet Nam and Mexico.

A vaccination programme should be comprehensive, use the latest scientific knowledge, and be well-designed for the individual country's poultry production system and based on the risks of the poultry species and geographical area. It should be applicable to the control of HPAI in endemic countries and usable as prevention in emergency programmes in countries at risk of introduction or imminent introduction in poultry.

Can vaccine stewardship be a tool for veterinary services to overcome avian influenza? Why might it be preferable to use this approach?

Vaccination stewardship helps veterinary services to develop appropriate vaccination programmes that produce sustained high-level immunity in vaccinated poultry. Every country using vaccination should adopt the principles of avian influenza vaccination stewardship.

Can vaccination alone control the disease? What other measures can be effective in controlling avian influenza?

One of the key points we emphasize is that vaccination alone does not resolve the problems of avian influenza. It must be combined with and added to existing and, preferably, enhanced biosecurity measures. It also must be subject to appropriate surveillance to identify infections, if any, in the vaccinated population.

What outcomes can be expected from the training in terms of improved control measures?

The main objective of the course is to provide participants with the knowledge needed to develop and implement appropriate avian influenza vaccination programmes. Although we focus on a single disease – HPAI – the approach varies from country to country. We are already seeing increasing uptake of systematic preventive vaccination against avian influenza and the course can help countries in this process.

Many countries have used vaccines, but avian influenza is still endemic in their territory; why is it difficult to eradicate the disease?

Vaccination was introduced in countries like China, Viet Nam, Egypt and Indonesia because the virus was already endemic. For a variety of reasons, it has not been possible to eliminate the virus by stamping-out methods. In Viet Nam, about 30 million poultry were destroyed in 2004, but it has not yet been possible to eliminate the virus or prevent severe cases of disease in humans. Vaccination has been successfully added as an additional measure to reduce the effects of the disease and largely prevent serious human infections. 

Repeated incursions of HPAI introduced from wild birds and subsequent spread to poultry have occurred in several countries. The cost of these outbreaks is remarkably high, and preventive vaccination should be considered in all countries with repeated and costly outbreaks. 

Vaccination stewardship helps countries where the virus is still present to explore ways to improve disease control. We recommend annual reviews of vaccination programmes to assess whether the goals of the vaccination programme are being met and whether changes to the programme are needed (changes in areas where vaccine is used, in vaccines, in the target population, and even changes in the way poultry is raised and sold).

A major misconception about vaccination is that it has led or will lead to endemic infection, when in fact it has been a response to endemic infection. We have good examples where vaccination has been used successfully as a preventive measure and endemic infection in poultry has not occurred.

About the experts

		Leslie Sims Leslie Sims has been involved in the prevention and control of HPAI since 1985, both as a government veterinarian and an FAO consultant for19 years. In 1997, he was working in Hong Kong when the first HPAI cases were identified, spearheading local efforts to eradicate the virus and prevent the recurrence of the disease. Recognizing the limitations of movement control and biosecurity, he became a strong advocate for vaccination as an additional measure to prevent HPAI.
		David E. Swayne David E. Swayne has been at the forefront of avian influenza research and control of avian influenza since 1987, starting as a faculty member at the College of Veterinary Medicine at The Ohio State University. From 1994 to 2022, he directed the U.S. Department of Agriculture's Southeast Poultry National Viral Disease Research Laboratory, focusing on HPAI, Newcastle disease, and other avian viral diseases. Since 2023, he has served as a private veterinarian, advising organic and poultry production companies, as well as national and global poultry industry groups. He also works with FAO and the World Organisation for Animal Health (WOAH) on HPAI prevention and control.