#17,841
As we've discussed often, and most recently in Preprint: Association of Poultry Vaccination with the Interspecies Transmission and Molecular Evolution of H5 Subtype Avian Influenza Virus, the changing impact of avian flu around the world is forcing many countries to reconsider poultry vaccination as a control method to save their flocks.
Until relatively recently, only China, Egypt, Indonesia, Vietnam and Hong Kong routinely used HPAI poultry vaccines, while the rest of the world - who admittedly only saw sporadic outbreaks - have abided by the 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 times, and situations, change. The abrupt global spread of HPAI H5 clade 2.3.4.4b, and its persistence in wild and migratory birds, has severely impacted global poultry production, and has already convinced some countries (e.g. France and Mexico) to begin vaccination.
But there are trade restrictions that prevent some countries from importing poultry from countries that vaccinate, and concerns over the safety of vaccination (see USDA Bans Import Of French Poultry Over HPAI Vaccine Concerns).
We addressed many of those safety concerns in last week's blog, and most of those appear solvable, assuming countries are willing to regulate the proper application of the vaccine and ensure that only updated, and effective vaccines are used, and maintain robust surveillance systems.
But in the past, countries that have adopted the use of poultry vaccines have rarely been so diligent. We've seen many instances (see here, here, here, and here) where substandard practices or older, ineffective vaccines have been used, which may have accelerated the evolution and spread of avian influenza viruses.
Yesterday WOAH (formerly OIE) released a lengthy statement on the rapidly changing avian flu landscape, and their rationale for now recommending previously shunned poultry vaccination as a `complementary approach' to AI control.
The prime focus of this document is to remove existing barriers to international trade for countries that choose to vaccinate some or all of their poultry, stating that vaccination does not change a country's HPAI-free status.
They do provide some caveats; countries opting for poultry vaccination must require the use of high-quality and updated vaccines, set up robust surveillance systems, require poultry producers to adhere to the control strategy, and ensure the traceability of the entire process.
Due to its length, I've only posted some excerpts. Follow the link to read it in its entirety. I'll have a postscript after you return.
Avian influenza vaccination: why it should not be a barrier to safe trade
Published on 28 December 2023
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].
(SNIP)
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 supportinspend the time, and resourcesg 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:
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.
- 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.
But it is a double-edged sword, with the potential - if mishandled - to make matters worse (see Vaccines: Vaccination and Antiviral Treatment against Avian Influenza H5Nx Viruses (Review Article).
The $64 question is whether we'll learn from the mistakes of the past, or simply go on repeating them.
