#17,484
Until recently - with the notable exceptions of China, Indonesia, Egypt, Vietnam and Hong Kong - most of the world's nations have eschewed the use of poultry avian influenza vaccination in favor of the long-standing OIE recommendation to `stamp out' HPAI infections by culling infected flocks.
That policy advised that vaccines should only be used as a temporary measure, stating that: `Any vaccination campaign must include an “exit strategy” i.e. a return to classic disease control measures.'
But with H5N1 spreading globally in wild birds - causing significant economic losses among poultry producers, and threatening to spill over into humans - many countries are now reconsidering their options (see WOAH: Rethinking Avian Influenza Prevention and Control Efforts).
Culling millions of birds is both expensive and traumatic, and with the virus now endemic in wild birds, likely to be a never-ending problem.
In theory, a properly applied, well-matched, and frequently updated poultry vaccination program should be an effective strategy against avian flu, at least in captive birds.
And we've seen some notable successes, including China's massive H5+H7 poultry vaccination program of 2017 which effectively shut down their H7N9 epizootic and the spillover of that virus into humans,
But in actual practice (see Egypt: A Paltry Poultry Vaccine), those can be difficult standards to maintain.
Even with China's success against H7N9 , H5N6 continues to circulate (apparently stealthily) in Chinese poultry and occasionally spills over into humans.
Several months ago, in WUR: 2 of 4 H5 Poultry Vaccines Tested Appear Effective Against H5N1, we saw a study out of the Netherlands that looked at 4 H5 poultry vaccines (2 currently in use, and 2 newer entries) and found the two older ones were ineffective.
Ineffective vaccines can often mask the symptoms of infection, but still allow the virus to spread, evolve, and potentially even spill over into humans. And that is, unfortunately, something we've seen previously:
Subclinical Highly Pathogenic Avian Influenza Virus Infection among Vaccinated Chickens, China).
Study: Recombinant H5N2 Avian Influenza Virus Strains In Vaccinated Chickens
EID Journal: Subclinical HPAI In Vaccinated Poultry – China
While the United States and many European nations have embarked on extended reviews of the safety and effectiveness of these vaccines before deciding whether to use them, some countries have apparently elected to put their faith into whatever vaccine is currently commercially available.
Last month France revealed the results of a year-long study into the use of an H5 vaccine to protect ducks (see Vaccination experiment of mule ducks in breeding against an HPAI virus), and last week announced their intention to begin a vaccination program in the fall (pending a final review).
The results of the vaccine experiment carried out on mule ducks have just been made official and show real effectiveness: https://agriculture.gouv.fr/experimentation-de-vaccination-des-canards-mulards-en-elevage-contre -a-virus-iahp . This is a step in the process that will determine the vaccine or vaccines that will ultimately be retained.
Based on the progress of the Action Plan launched on December 22, France plans at this stage to vaccinate, as a preventive measure, commercial duck farms throughout the national territory in the fall of 2023. The vaccination strategy will be finalized in month of June, and decided by the Minister.
In contrast, yesterday the UK's DEFRA reiterated their policy (which, admittedly could change) against the use of poultry vaccines (except in zoos).
Guidance
Avian influenza (bird flu) vaccination
Updated 5 June 2023
1. UK bird flu vaccination policy
The current UK policy on bird flu vaccination is not to permit the vaccination of birds (outside of zoos in England and Northern Ireland) either for disease prevention or as a disease control response.
Stamping out remains the most effective means of controlling an outbreak. Since October 2021 an unprecedented number of outbreaks have been reported throughout Europe and in several regions of the world, reaching new geographical areas and causing devastating impacts on animal health and welfare.
In the UK, concerns around the impact on traditional and free-range poultry systems, the number of birds that need to be culled, and the development of new vaccine technology mean that the development of effective DIVA (differentiating infected from vaccinated animals) vaccines for use as a preventive measure is now a key priority for government and industry.
The current available vaccines with UK marketing authorisations have disadvantages in that, although they are able to reduce mortality, it’s possible that some vaccinated birds would still be capable of transmitting the disease if they became infected whilst not displaying clinical signs.
Many trading partners currently prohibit trade from countries that vaccinate poultry for this reason. Without enhanced surveillance there are concerns that undisclosed disease could be circulating and this would increase the time taken to detect and eradicate the virus. Vaccination may also induce a false sense of security, resulting in a relaxation of biosecurity and vigilance.
This is why vaccines are only licensed for zoo birds.
Vaccination of zoo birds is permitted in England and Northern Ireland, subject to meeting eligibility criteria and receiving authorisation. Only zoos or collections holding a current zoo licence can apply for an authorisation to vaccinate. Vaccination of zoo birds against avian influenza is currently not permitted in Scotland or Wales.
Biosecurity, early reporting, rapid action, culling and surveillance remain the most effective ways of protecting against and controlling an avian influenza outbreak. More information can be found in the GB notifiable avian disease control strategy and Defra’s guidance.
Find out how to:
spot and report bird flu
prevent bird flu and stop it spreading
A joint industry, cross-government avian influenza vaccination task force has been established to explore options and develop recommendations for the use of vaccination of poultry as a preventative measure against highly pathogenic avian influenza (HPAI) in the UK.
Like most modern technologies, poultry vaccination is neither inherently good or bad. It can, however - particularly if it is wielded improperly - become a double-edged sword.
AI vaccination can prevent the deaths of millions of captive birds - avoiding huge economic losses and potential food insecurity - but it can also provide the virus with the means to spread (and evolve) under the radar (see MPR: Poultry AI Vaccines Are Not A `Cure-all’ & New Scientist: The Downsides To Using HPAI Poultry Vaccines).
It can even be argued that the difficult situation we find ourselves in today with H5N1 has been partially exacerbated by the improper or suboptimal use of AI vaccines over the past 20 years. We've certainly seen plenty of warnings to that effect over the years.
But the past is what it is, and we can only control where we go from here; Primum non nocere.
If we are (as it appears) going to go down the AI vaccination road, we'd better do so with our eyes wide open. While we might desire a quick fix, using poorly-matched vaccines, or applying them improperly or inconsistently, could make matters worse.
And right now, the last thing we need to do is give H5Nx a helping hand.
