So far, 2022 has been a deadly year for the world’s birds. Avian influenza continues to rise, and this is hot on the heels of two years that the U.S. CDC says saw more outbreaks than the previous four years combined. Each outbreak of avian influenza can have huge ramifications for animal and human welfare. And, of course, a devastating impact on the economy and global food security.
Just a single outbreak in the Netherlands in 2003 cost an estimated 150 million euros and the culling of some 30 million birds. Right now, other countries – like the UK – are facing similar losses.
A look at the current spread of avian influenza and the evolving discussion on vaccination.
Biosecurity and hygiene is currently the first line of defense against avian influenza in most countries. While this can limit exposure, this is not fool proof as outbreaks grow in size and scope each year.
The U.S. CDC has reported that globally “there were more outbreaks reported in 2020-2021 than in the previous four years combined.” What’s more, viruses are cropping up in countries that have been clear of avian influenza for many years – like Canada.
The CDC reports that, in December 2021, HPAI A (H5N1) viruses were detected in birds in Newfoundland. This is the first identification of this virus in the Americas since June 2015.
Vaccines have been considered as a potential control measure against avian influenza, but these are often not widely available or used in many markets. There has been some recent discussion about re-evaluating vaccination though.
According to Julien Denormandie the French agriculture minister,There is “no other solution in the long term than to have vaccination.”
Vaccines are often not used due to concerns about trade disruptions.
In the past, export bans have been enforced on countries with vaccination policies. This is due to concerns such as not being able to differentiate vaccinated animals from infected animals, which occurs if a vaccine is not a 'DIVA vaccine'. DIVA vaccines and diagnostics :DIVA stands for Differentiating Infected from Vaccinated Animals. For Avian influenza, this can be achieved by using a vaccine based on a different strain (e.g. H5N2) than the current field strain (e.g. H5N1) and using a serological test that can differentiate between vaccine-induced antibodies (e.g. against N2) and antibodies against the field virus (N1).
Current thoughts on whether there may be scope for vaccination in the future:
The loss of millions of birds is a significant welfare issue that requires considering all avenues of prevention.
The Poultry Veterinary Study Group of the EU published a paper in October calling for an ‘open-minded evaluation’ of vaccines, saying it would ‘offer better protection to poultry'.
The French minister of agriculture sees vaccination as a long-term, viable solution in the face of rising losses.
Though it may be too late to mitigate the impact of the current outbreaks, vaccination could become a future prevention measure alongside alongside biosecurity and other tools.
The info graphic below shows the impact of Avian Influenza in 2021.
