Vaccinating against avian influenza is not new. Poultry producers in Mexico have been vaccinating their flocks for nearly 30 years now. In Canada, vaccinating against avian influenza has become a hot-button issue that has no clear answer. In a recent Canadian Poultry webinar on biosecurity, Jean-Pierre Vaillancourt, professor at the University of Montreal, talked through the pros and cons of vaccination, provided an update on the situation in France, and offered insight into what could be involved in a vaccination strategy in Canada.
The pros and cons of vaccination
Around the world, many countries have been vaccinating flocks for years, particularly against the H7 and the H5N2 viruses, and now against the H5N1 virus. Some of the countries that currently vaccinate their flocks against avian influenza include China, Hong Kong, Indonesia, Mexico, Vietnam and France. The latter began its efforts in October 2023. With less than a year of experience under its belt, France serves as a strong test case for Canada, as the country’s poultry sector discusses whether or not it wants to develop its own strategy.
Vaillancourt laid out the obvious pros to adopting a vaccination strategy during his biosecurity webinar. Protecting animals from mortality, reducing the need for poultry depopulation, and reducing viral excretion and animal susceptibility to infection came out as strong reasons to vaccinate. In recent months, the focus has shifted from protecting animal health to reducing human exposure to avian influenza viruses to protect human health.
At the time of writing, the U.S. Centers for Disease Control and Prevention had just issued a statement reporting three new cases of bird flu infections in Colorado poultry farm workers, taking the total number of human cases in the U.S. to 13 this year.
“There’s a big growing concern internationally that this virus could become zoonotic,” Vaillancourt says. “It cannot be easily transmitted from infected animals to humans, and it cannot be transmitted right now between humans. But this could change.”
The decision to vaccinate does come with consequences, though, Vaillancourt pointed out. The risk of silent virus circulation in vaccinated poultry populations and potential trade restrictions as strong reasons not to vaccinate.
Trade restrictions are not out of the ordinary. Following France’s decision to vaccinate its duck flocks, both Canada and the U.S. announced trade restrictions. The Canadian government suspended poultry imports from France, but did not extend that suspension to the rest of the European Poultry Trade Region. At the time of the announcement, the Canadian Food Inspection Agency said it was working with the French authorities to conduct an assessment to evaluate the potential risks of the vaccination campaign.
Recent revelations from France
Vaccination comes at a hefty cost, too, and implementing a robust surveillance program has its challenges. No one knows this better than French poultry producers.
In a recent interview, Jean-Luc Guerin, an avian virologist based in France, provided an update on France’s ongoing vaccination efforts. Guerin is a man who wears many hats. He is a professor of poultry production and medicine at the national veterinary school in Toulouse (ENVT). He is director of the IHAP joint unit at INRAE-ENVT, a multidisciplinary public research institute for animal infectiology. He is also head of the VIRAL group and director of the avian biosecurity chair. In a nutshell, he understands what Canada is up against should its poultry sector decide to take the same route.
The first setback France faced was the cost of implementation. The ministry of agriculture projected the annual cost at 104.82 million euro ($157.14 million), 85 per cent of which was to be paid for by the state. Industry paid approximately 15 per cent or 15.7 million euro ($23.54 million) of the overall cost to vaccinate; the state paid the rest.
It wasn’t the vaccine itself that made up the bulk of the cost, though. What really set both industry and the state back was the cost of supervision and surveillance. Purchasing and getting the vaccine to farms cost the state approximately 27.4 million euro ($41.08 million). Surveillance, including vet visits and lab analysis, made up the rest of the costs. The cost to vaccinate alone amounted to 31.94 million euro ($47.88 million).
During the vaccination process, the birds must be handled by trained catching crews and the vaccination process itself must be supervised by a veterinarian. “You need a lot of manpower with training for this,” Guerin says, adding that it’s important that they’re trained on biosecurity protocol.
The two accepted vaccines, one from Boehringer Ingelheim and the other from Ceva, have two different modes of injection. The latter is injected intramuscularly, which requires specific training. A veterinarian must be present to ensure the vaccination is correctly administered, that any leftover vaccines are properly disposed of, and the crew strictly adheres to biosecurity and traceability protocols.
But it’s not just the vaccination process that requires the presence of a vet. According to EU regulations, ongoing monitoring and surveillance are required. Passive surveillance is based on the detection of dead birds. Up to five dead birds are tested each week using PCR analysis. Guerin says this proved challenging at the beginning of the campagin, as sampling guidelines needed clarification in order to be properly implemented by farmers.
Active surveillance protocols were in place as well. Veterinarians were required to visit the farm each month to conduct a clinical analysis of the flock. During this visit, they were expected to sample 60 birds using tracheal swabs and cloacal swabs.
“Additionally, we are doing 20 blood samples for serology, and this for all the vaccinated flocks,” Guerin says. “It’s a lot.”
In total, vets are expected to visit a flock two to three times throughout its life cycle. Guerin says scientists and industry experts are looking for ways to simplify the process without affecting its sensitivity, but that would mean adapting the regulation. To do this, they need to demonstrate that alternative sampling methods are just as effective.
One suggestion is to forgo the tracheal and cloacal swabs and, instead, use a targeted sampling of dead birds, associated with dust samples as is done in salmonella surveillance programs. This type of surveillance could be done without a vet present. It’s quick and convenient, and costs significantly less.
“We need to provide robust scientific data to convince the decision makers, and that’s the most difficult part because I know it is very difficult to change this type of regulation,” Guerin says.
Researchers are also looking into vaccinating at the hatchery level. Because the two accepted vaccines are administered in different ways, they cannot be injected using the same machine.
“It’s not a problem of science,” Guerin says. “It’s a problem of investment and training and strategy based on the choice of the vaccine.”
It’s difficult to know if the investment was worth it, especially given the impact on trade. The official assessment is not yet complete. At the European level, avian influenza cases dropped significantly since October 2023 when France began its vaccination campaign.
Between October 2022 and May 2023, France reported 364 outbreaks. Between October 2023 and May 2024, just 10 cases were reported. Of those, three outbreaks occurred on duck farms. Of those three, one outbreak occurred in a completely vaccinated flock. The other was a very young flock with only one of two injections complete, and the other was a breeder flock that was not vaccinated at all. The other seven outbreaks occurred in turkey and layer flocks.
While the assessment is not complete, Guerin says he’s pretty sure that the vaccination campaign successfully reduced the number of outbreaks.
The Canadian approach
As Canada’s leading biosecurity expert, Vaillancourt will always emphasize the importance of bolstering on-farm and regional biosecurity. He’s worried that adopting a vaccine could give farmers a false sense security that could lead to a reduction in their compliance with biosecurity measures. This could mire any efforts to eradicate the virus altogether.
There are many factors to consider, too, he said, pointing to the need for a strong surveillance program with good interventions. Any vaccination campaign will need to consider social acceptability and the potential impact on Canada’s poultry sector. There’s also a big question mark around the vaccine itself. Currently, there are 57 vaccines for avian influenza in the world. None are available in Canada.
“It’s a challenge to do all this, and the cost benefit for the countries that are working with this, well, the jury’s still out,” Vaillancourt concludes. “That should all be part of our thinking process as we move forward.”
