Will the vaccine be the miracle solution to the epizootic?

And once more. Chickens, pigeons, geese and other free-range poultry are once again confined. When the Covid-19 locked the French at home for weeks in 2020 and 2021, it was avian flu that hit bird farms. A disease that comes back regularly, much like the human flu, but which seems to spiral out of control. Since this summer, already 770,000 animals have been slaughtered for the 2022-2023 season. A balance sheet that has more than doubled since the previous press release from the Ministry of Agriculture on October 12, reporting the slaughter of more than 330,000 animals. The level of risk linked to highly pathogenic avian influenza (HPAI), commonly known as bird flu, has been raised to “high” throughout metropolitan France by a decree published this Thursday in the Official Journal.

The previous 2021-2022 season had already been catastrophic with a total of more than 20 million poultry slaughtered, in infected farms or as a preventive measure, to stop the progression of the virus and an “out of control” epidemic, according to the Minister of Agriculture at the time, Julien Denormandie, now in charge of Housing. So how to explain that this flu, also called avian influenza, takes on such a scale? How to curb it? Will the vaccine be a miracle solution? Claire Hautefeuille, veterinarian, epidemiologist and researcher at CIRAD (Centre for International Cooperation in Agricultural Research for Development), provides some answers.

Why has avian flu taken on such proportions this year?

The unprecedented episode by its magnitude has upset the poultry industry. Certain territories, such as Pays-de-la-Loire and Brittany, spared during previous crises linked to the virus, have this time also been affected by the epizootic. Repeated confinements force mentions of free-range farming to be suspended in the specifications of reputable productions, such as duck foie gras from the South-West or eggs from Loué. And France is not the only one affected, the virus is present in 17 other European countries, according to the French platform for epidemiological surveillance in animal health (ESA). Domestic birds and poultry must be confined across England since November 7.

The virus started to hit French farms again at the end of July, exceptionally early. In the end, the poultry will only have been allowed to taste the outdoors for a few months. “This year, there has been a major paradigm shift: before, we had waves of migration with an onset of infection around October-November”, explains to 20 minutes Claire Hautefeuille. While this year, outbreaks were observed “from the beginning of August”, she continues. This premature arrival of infections is explained by “the permanent presence of the virus in wild birds in Europe”.

How to stem the epizootic?

There are several measures in place to contain contamination and control the circulation of the virus each year. There is in particular the slaughter of poultry, which is practiced a lot in France. “But also biosecurity measures such as containment, cleaning of equipment,” adds Claire Hautefeuille.

Biosecurity is the health protection of farms. It makes it possible to slow down transmissions between infected subjects and uncontaminated subjects. Concretely, we separate the different farms from each other, and we avoid contamination by truck or by people, “it’s a kind of social distancing at the level of the farms”, explained at the beginning of the year to The Express Jean-Luc Guérin, professor of avian pathology and director of an INRAE ​​infectiology laboratory at the National Veterinary School of Toulouse. Transmission monitoring is also important. This is what was called during the coronavirus epidemic the “test, trace”. Except that instead of being isolated, infected birds will be slaughtered.

Is the vaccine the miracle solution?

What about vaccination then? “It is generally the last method implemented”, according to Claire Hautefeuille. Initially reluctant to vaccinate against HPAI, poultry professionals are now eagerly waiting for vaccines to be authorised. An experiment is also underway in Europe. But for the moment, in France, and more widely in Europe, no vaccine has yet received the green light for its marketing. “You have to vaccinate, defends AFP Lionel Candelon, breeder in the Gers and president of the Angry Ducks association. It’s the only solution we haven’t tried. (…) If it doesn’t work, at least we will have tried. The risk is that we slaughter 15 million poultry. ” Otherwise, ” how to continue ” to produce, abounds the president of the chamber of agriculture of Vendée, Joël Limouzin, questioned by AFP. Vaccines exist, and are used in countries where the disease is endemic such as Egypt or Indonesia “but not for countries which face the virus periodically”, specifies Claire Hautefeuille.

If it blocks, it is mainly for political reasons. If a country that exports its poultry vaccinates its farms, those that import these products will no longer want to do so. “France risks no longer being able to export”, sums up Claire Hautefeuille. Indeed, “if vaccination is complicated today it is because then, the identification of the circulation of the virus within the vaccinated population can be more difficult”, explains the veterinarian. “There is therefore a risk that the virus will circulate quietly,” she continues.

“Hence the importance of having effective surveillance systems in the territories where vaccination is implemented, as recommended by the World Organization for Animal Health (OMSA)”, emphasizes Claire Hautefeuille.

How can vaccination be implemented?

Logistically, a vaccination campaign would take time. The vaccine should be injected into the poultry, one at a time. There is also the vaccination of chicks, but again, it would be chick by chick. In addition, the other difficulty is to have “an effective vaccine against the strains which circulate despite the possible rapid mutations of these strains”, warns Claire Hautefeuille. Thus there are two solutions: “either a vaccine which has a field of action broad enough to cover all the strains but which risks being less effective, or a vaccine adapted to each strain”, she develops.

Parries employed today are not sufficient. Both breeders and researchers seem to agree on this point. Moreover, these growing epidemics come at a cost. Even before the resumption of the epizootic this summer, the bill for avian flu amounted to more than a billion euros for the French State to compensate the losses of professionals.