Avian influenza: Unspeakable damage and unexplainable consequences

17-01-2023 | Health | Article

Chairman of the IEC working group Avian Influenza, Ben Dellaert gives an overview of the current bird flu crisis. Photo: Fabian Brockötter

With millions of commercially raised birds affected by avian influenza on thousands of premises in major poultry-producing nations, the call for vaccination is getting louder. So much so that the IEC and IPC drafted a joint statement to convince the industry, international organisations and governments to allow vaccination while mitigating the risk of trade barriers.

Since early spring 2022, more and more alarm bells have started to ring as the poultry sector and beyond realised that the avian influenza virus wasn’t behaving as expected. Of course, the devastating disease is not new – it’s an unfortunate annually reccurring event. “We had already seen a change in disease patterns over the last couple of years,” says veterinary epidemiologist, Professor Arjan Stegeman.

As a member of the International Egg Commission (IEC) global expert group on avian influenza, Stegeman saw the disease evolve from a very rare event until 2004 into an annual event since 2014. “Normally the virus would peak in December and then slowly fade out. This year that didn’t happen and the virus remained present year round, even during summer when we expected it to die off under the dry and warm conditions.”

His findings are corroborated by the European Food Safety Authority (EFSA). The European Centre for Disease Prevention and Control, and the EU Reference Laboratories reported an unprecedented number of highly pathogenic avian influenza (HPAI) virus variants detected in wild and domestic birds from June to September in Europe. In previous years, no cases, or just a few, were confirmed during the summer period. The overall 2021-2022 HPAI season has produced the largest epidemic so far seen in Europe.

The ongoing HPAI season was extremely damaging, with a total of 2,467 outbreaks in poultry and 47.5 million birds culled in affected establishments. In addition, the HPAI A(H5N1) virus also crossed the Atlantic Ocean for the first time in autumn 2021, spreading from Europe to North America via migration routes, causing a severe epidemic in poultry in several Canadian provinces and US states affecting 40 million birds and counting.

“It is time to stop considering avian influenza and the vaccination as a taboo and react with sense of urgency …”

EFSA recommends the rapid implementation of suitable and sustainable HPAI mitigation strategies, including appropriate biosecurity measures and surveillance strategies for early detection. Medium to long-term prevention strategies should be considered in densely populated areas and in poultry production systems highly susceptible to avian influenza exposure.

“With the virus omnipresent in wild birds, leading to single introductions in commercial operations time and time again, the current ‘stamping out’ strategy does not eliminate the virus anymore. If we do not change how we confront this disease, the poultry industry is in serious danger,” notes Stegeman.

Vaccination against avian influenza

Getting the virus under control is necessary for multiple reasons. Most pressing for the poultry industry itself is the limitation of direct damage caused by the disease, for business continuity and – no less important – for the support of governments that pick up part of the tab by compensating for the direct and indirect costs of the culling measures.

“But there is more to it than that,” says Ben Dellaert, chair of the avian influenza expert group of the IEC. “In the current situation, outdoor farming becomes next to impossible from a disease perspective. At the same time, our industry knows that our licence to produce – our consumer acceptance – demands the use of alternative housing systems. But with avian influenza we find ourselves in dire straits. It will become increasingly difficult to explain to consumers that we produce valuable animal protein at the expense of millions of birds dying of a disease. This demands new solutions.”

As with many poultry diseases, Newcastle disease to name but one, vaccination is the most obvious tool to combat avian influenza. And that is exactly what Dellaert’s avian influenza expert group is working on. “We want to make vaccination possible and acceptable. For that we have drafted a joint position held by both the International Egg Commission and the International Poultry Council, asking international animal health bodies and all our member nations to convince the national chief veterinary officers to endorse vaccination.”

As Dellaert notes, there are multiple hurdles before vaccination can be implemented. “Of course there are technical questions. Which vaccine for which virus strains? Can we differentiate between vaccinated and infected birds? What guidelines should our avian influenza surveillance programme give? That said, technical issues can be overcome as lots of research is ongoing (see box). The real challenge that has to be overcome before we can move forward is trade restrictions. If vaccination leads to trade restrictions, it will be difficult to implement a new avian influenza strategy for exporting countries.”

From left to right, Chad Gregory, Arjan Stegeman and Ben Dellaert discuss ways to implement an AI vaccine strategy with members of the International Egg Commission. Photo: Fabian Brockötter

Trade

Avian influenza has often been used and misused to close borders out of fear of infection and to protect local markets. Despite the fact that the virus has become a global threat to poultry production, these reflexes still pose a threat.

At this time, vaccination is in the toolbox of some non-exporting countries. Exporting countries are hesitant due to possible consequences, as voiced by Chad Gregory, president of the United Egg Producers in the US. “Our egg producers all support a vaccine strategy moving forward, as they bore the brunt of the influenza outbreak. To be honest, the layer operations are scared to death in this game of Russian roulette. However, in my opinion, it is highly unlikely that our US poultry meat producers will see vaccination as an option. Their fear is that they will take a big hit in exports, worth US$ 3-4 billion annually.”

“Vaccination is too valuable a tool not to use…”

If the industry gets the US chief veterinary officers on board on vaccination, the government official needs to convince about 60 colleagues in importing countries to ensure supple export flow. “It’s difficult to predict how this will pan out. Having said that, if the virus sticks around for another 6 months, damage payouts will push the government in the direction of vaccination,” Gregory added.

From his European perspective, Stegeman warns that the broiler industry is in no way safe from infection as broiler farms with traditional production systems (closed houses) have already been hit in Europe. He adds: “Avian influenza has to be stopped in its tracks as there is a public health side to it as well. The current virus strain is not dangerous to humans but we do see mutations and have even witnessed cross species infections to mammals recently.”

Vaccination is too valuable a tool not to use. “And even if we don’t have a perfect vaccine, it can still be valuable. Over the years, various animal diseases have been controlled by imperfect vaccines. Newcastle disease, foot and mouth disease, and Aujeszky’s disease are all good examples of that.”

3 trials, 3 vaccines
Before the end of 2022, 3 research facilities hoped to see the first results of a small-scale vaccine trial. In France, Italy and the Netherlands, multiple vaccines are being tested in closed quarters to get an idea of how they protect and if there is any virus shedding. Although promising so far, controlled field trials have to follow, pushing the horizon for actual vaccination years ahead.
Wageningen Bioveterinary Research (WBVR)

Dr Nancy Beerens of Wageningen Bioveterinay Research heads one of the lab trials with avian influenza vaccines. Photo: ANP

is one of the labs testing avian influenza vaccines of 3 different pharmaceutical companies. The trial tests vaccines against the current H5 viruses in laying hens. “More information about the potential vaccines against bird flu is required before these can be applied in the field,” explains avian influenza researcher, Dr Nancy Beerens, in Poultry World’s Dutch sister publication, Boerderij.
The research is being done under the auspices of the Dutch Ministry of Agriculture, Nature and Food Quality. This first vaccine trial is being carried out at the animal facilities in the high containment unit of WBVR. The modern vaccines were developed by 3 different pharmaceutical companies, Ceva (which already has registration in the US and elsewhere), a new vaccine from Huvepharma, and a third, also new, vaccine about which – at the request of the manufacturer – WBVR has not provided any information.
The vaccines being tested are based on different technologies. “In this trial we are testing the effect of the vaccines on clinical signs of disease. The effectivity of the vaccines against the spread of the virus is another important parameter in the study,” says Beerens. “We expect the new types of vaccines we are testing in this trial to provide better protection against the spread of the virus than previous vaccines. It is also possible to distinguish between vaccinated and infected animals using specific diagnostic tests.”
Several European countries have started vaccination studies. “The results of these studies are very important for future European agricultural policy which may allow the vaccination of poultry.
Vaccination will take time
The avian influenza vaccination research at WBVR is the first step in research aimed at combatting bird flu with vaccination. The information obtained from this research will be used for future research, such as a field trial. Unfortunately, poultry farms will not be able to vaccinate against the virus in the short term. “We are not there with one trial, even if it is a success,” Beerens emphasises. A field trial will probably follow in January, which will then take a year to see whether the vaccines provide long-term protection and how the vaccination works in day-to-day poultry farming practice.
In addition, new vaccines (including the 3 in the trial) will first have to be registered by the manufacturer for approval. Beerens said had not been possible, in practice, to vaccinate in 2022-23 flu season, adding that she has doubts that everything would be ready to start vaccination in the upcoming season (starting October 2023).

Moving in the right direction but at a slow speed
With a strong know-how on new technology vaccines for avian influenza, vaccine manufacturer, Ceva animal health, has ample experience in controlling the disease. Time for Poultry World to sit down with their experts, Sylvain Comte, Christophe Cazaban, Bertrand le Tallec and Mustafa Seçkin Sandikli. The veterinary heavyweights are optimistic on the role a vaccine can play to mitigate the damage avian influenza causes.
“If the avian influenza outbreaks of the last season have taught us one thing, it is that the ancient solution of stamping out will not help us anymore,” said Comte. He emphasised that this is not the conclusion of a vaccine producer alone: “Industry and animal health representatives recently congregated at the International Alliance for Biological Standardization (IABS) HPAI meeting in Paris. Here we witnessed an important shift in the avian influenza discussion. Previously, every conversation on vaccination always ended with someone summing up the impossibilities due to potential trade restrictions. However, in the recent meeting it was established that the trade argument is no longer a prerequisite in taking steps forward.”
However, even without the fear for trade barriers, the experts state that there are still many steps in front of us. “There are many misconceptions about the old ‘killed’ vaccines, which we have to take away,” knows Ceva’s scientific director, Christophe Cazaban. He continued: “Our experiences with the vaccine in multiple countries has taught us that we can protect against multiple virus strains, reduce shedding and distinguish between vaccinated and infected birds (DIVA). The challenge now is that we move from countries with an endemic avian influenza situation with low monitoring to a highly controlled region where we have and want to maintain strict monitoring. That needs research, extra assurances and local scientific evidence and documentation. That is what is currently underway.”
It is time to stop considering avian influenza and the vaccination as a taboo and react with sense of urgency says Mustafa Seçkin Sandikli. “Misconceptions due to the inactivated vaccines still cause repeated questions, the loss of time and the frustration. One of the remarkable notes from the last IABS-HPAI meeting in Paris was that the vaccination is a crucial part for prevention strategy and the ideal vaccine is indeed a new technology vaccine like r-HVT vector vaccines. While the biosecurity measures still remain the fundamental pillar, now the following points are the expected values from the new technology vaccines: protection, transmission control, DIVA (distinguish infected from vaccinated birds).”
He added: “With more than 10 years of experience with around 2 billion doses of r-HVT vector avian influenza vaccine administration, Ceva is confident and motivated to meet the above expectations with a unique value addition to poultry.”
His colleague, Bertrand le Tallec, continues: “The demands for the avian influenza vaccine are much stricter compared to – for instance – the human Covid vaccine. And as the avian influenza situation is deemed less urgent by society at large, the pressure on governments to give a clear direction forward, is less than with Covid.”
According to Le Tallec a clear path for avian influenza is needed. Sandikli adds: “Until now, 300 million birds are being vaccinated with our r-HVT-H5 vaccine yearly. Meeting an increasing demand will need a lead time for a good vaccine production plan. A clear strategy and commitment will help us to stock up to meet the increased demand. Ceva has applied for registration in France and the paperwork for EU registration is underway.”
Comte adds: “We expect that our vaccine will get EU registration in 2023; however, that doesn’t automatically mean we can administer it. Registering and implementing a vaccine strategy are 2 separate things. That said, we are more than ready to use our vaccine as a tool in an approach where biosecurity, stamping out of infected flocks and protection by vaccination go hand in hand. We are confident that this will significantly help to mitigate the damaging effect of avian influenza.”