DUTCH researchers trialling avian influenza vaccines in a field study have said two have been found to protect laying hens from the disease eight weeks after vaccination.

In the field study, which started in September 2023, 1,800 laying hens were vaccinated and housed on two commercial poultry farms.

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The trial at these two farms will run until the third quarter of 2025.

On four occasions during this study, a number of the vaccinated chickens will be infected with bird flu to study the effectiveness of the two applied test vaccines against the HPAI H5N1 virus.

Evelien Germeraad of Wageningen Bioveterinary Research (WBVR), said: “We examine virus transmission – transmission – after vaccination, as well as survival rate, virus excretion and immune response.

Transmission

“Based on these performances, we assess the effectiveness of the vaccines.”

This first transmission study was conducted eight weeks after vaccination.

The field study was commissioned by the Dutch Ministry of Agriculture, Nature and Food Quality (LNV).

Partners in the field study alongside WBVR are Royal GD, Faculty of Veterinary Medicine (Utrecht University) and Wageningen University & Research.

The field study is being conducted with two different vaccines: VECTROMUNE® AI from CEVA Animale and VAXXITEK HVT-IBD-H5 from Boehringer Ingelheim.

Vaccinated birds

None of the vaccinated chickens became infected after contact with the avian influenza virus, the R value of the vaccinated group could not be quantified.

In the control groups, chickens did become infected (R value of 1.3).

The transmission trial will be repeated three more times during the ongoing field trial.

Based on the positive outcome of this first transmission study, the Ministry of LNV is already preparing next steps aimed at enabling bird flu vaccination in the Netherlands and setting up a monitoring programme.

The ministry expects the first pilot study with a larger group of commercial poultry farms to start after summer 2024.