Avian influenza vaccines protect laying hens - Field study
A long-term study conducted by Wageningen Bioveterinary Research (The Netherlands) aims to determine whether vaccination under field conditions can provide long-term protection for layer flocks against the HPAI H5N1 virus (clade 2.3.4.4b) and reduce within-flock transmission (R<1). A transmission study was performed 8 weeks post-vaccination with layer hens housed under field conditions. In addition to the main output, which is the assessment of the level of transmission, other variables such as chicken survival, virus shedding, and humoral and cellular immune responses were studied to assess the effectiveness of vaccination with VAXXITEK HVT+IBD+H5 or VECTORMUNE AI vaccines in poultry against HPAI H5N1 virus infection.
In the field study, which started in September 2023, 1,800 laying hens were vaccinated and housed on two commercial poultry farms. 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 challenged. The estimated R for the vaccinated groups could not be quantified as none of the inoculated chickens became infected. The two bird flu vaccines currently being tested in a field study have been found to protect laying hens from the disease eight weeks after vaccination.
R-value: The R number is a way of rating virus ability to spread. R is the number of chickens that one infected chicken will pass on a virus to, on average.
