Thursday, January 04, 2024

France Reports An Avian Flu Outbreak In A Vaccinated Flock


France, which decided last summer (after months of testing) to go ahead with poultry vaccination against HPAI H5, ordered that certain high risk flocks receive two doses of the vaccine last fall. In early December - citing unspecified `New scientific evidence ' the French MOA Ordered a 3rd Vaccine Dose For High Risk Ducks.

We've looked at the pros and cons of poultry vaccination against HPAI numerous times, including:

WOAH Statement: Avian Influenza Vaccination: Why it Should Not Be a Barrier to Safe Trade

Preprint: Association of Poultry Vaccination with the Interspecies Transmission and Molecular Evolution of H5 Subtype Avian Influenza Virus

USDA Bans Import Of French Poultry Over HPAI Vaccine Concerns

Poultry vaccination is a controversial subject, with many countries (including the United States and the UK) holding off on embracing any vaccination policy. 

While a properly applied, well-matched, and frequently updated poultry vaccination program should be an effective strategy against avian flu - at least in captive birds - the vaccine doesn't always prevent infection.

The concern is that may lead to the asymptomatic spread of the virus - and potentially - the generation of vaccine escape variants (see EID Journal: Subclinical HPAI In Vaccinated Poultry – China). 

We've also seen many instances over the years where suboptimal vaccines or vaccination strategies have been used around the world (see here, here, and here).

Today France is reporting an outbreak of HPAI H5 on a vaccinated duck farm in Vendée in the western part of the country.  While details were limited on the French MOA site, the Préfet De La Vendée has released the following detailed communique. 




A first outbreak detected in Vendée in a duck farm

An outbreak of highly pathogenic avian influenza was confirmed on January 2 in a duck farm in the commune of Notre Dame de Riez in the Vendée department.

To avoid any risk of spreading the virus to other farms, the prefect of Vendée has issued an order defining regulated protection zones (ZP) and surveillance zones (ZS) which are respectively set up within a radius of 3 and 10 km around the contaminated establish

Within the 3 km radius, the municipalities (or parts of municipalities) concerned are: Notre Dame de Riez, Saint Hilaire de Riez (east of the D38 and D69), Soullans (east of the D69, south from the D82 and west of the D32), Commequiers (south of the D82).

In the 10 km zone, the municipalities concerned (or parts of municipalities) are: Saint Hilaire de Riez (west of the D38 and D69), Soullans (west of the D69, north of the D82 and east of the D32), Commequiers (north of the D82), Saint Gilles Croix de Vie, Le Fenouiller, Givrand, Saint Révérend, Coëx (north of the D6 and west of the D21), Apremont ( west of the D21), Saint Maixent sur Vie, Challans (south of the D948), Le Perrier, Saint Jean de Monts (east of the D51, north of the D38B and south of the avenue Valentin).

In these areas, all places where poultry and captive birds are kept are subject to specific requirements. In particular, the movements of poultry and other captive birds are prohibited, except for exemptions granted by the Departmental Directorate for Population Protection (DDPP). Surveillance is also reinforced by carrying out self-checks which are made compulsory by prefectural decree.

Poultry farms in regulated areas will be subject to increased surveillance.

In addition, as part of measures to combat the spread of the virus, an operation to depopulate the 8,700 ducks present on the farm affected by the avian influenza outbreak was carried out. State services, and in particular the DDPP, are mobilized alongside the breeder, who will be compensated for the losses suffered by this operation.

The ducks on this farm had all been vaccinated against highly pathogenic avian influenza (HPAI) last November, in accordance with regulations. It is recognized that vaccination does not completely eliminate the risk of infection of poultry in the event of introduction of the virus into the farm. On the other hand, vaccination reduces virus shedding and viral circulation.

France has been at high risk with regard to HPAI since December 5, 2023. Players in the sector must ensure, throughout the territory, the strictest application of biosecurity measures to prevent the virus from spreading. enter farms via wildlife and human activities, and avoid its spread between farms.

         (Continue . . . .)

There is no mention whether these ducks had received the recommended 3rd dose in December, or what symptoms (if any) these ducks exhibited.  No report has appeared (as of this writing) on the WOAH WAHIS dashboard. 

While the breakthrough infection in a single flock is not unexpected, this is a reminder that poultry vaccination isn't a panacea for avian flu. 

France, and those countries considering the vaccination of their own poultry, will be watching carefully to see whether other vaccinated farms are affected in the weeks and months ahead.