Evaluation of the effectiveness of some H5N1 avian influenza vaccines
The study was conducted to evaluate the virulence of the avian influenza virus strain A/H5N1 clade 2.3.2.1e in the field and the protective efficacy of three types of vaccines (D7+rD8, Navet-fluvac2, Re-5) on experimental chickens. The results showed that the test virus strain had high virulence with an IVPI score of 2.91 and a clinical score of 2.38 for nasal discharge, causing 100% mortality in the control chickens. In the experimental chickens with a uniformly negative immune background (95.98%), all three vaccines were capable of inducing strong antibody responses. Among them, the D7+rD8 vaccine achieved the highest efficacy with 100% of chickens developing protective antibodies (GMT 7.3 log2), followed by Navet-fluvac2 (92%) and Re-5 (90%). After virulence boosting, all three vaccines provided excellent protection with a survival rate of 100%, and the chickens remained healthy with no clinical symptoms. These results meet the standards of TCVN 8685-9:2014, indicating that this is one of the effective solutions for controlling the current H5N1 influenza epidemic.
