Experimental H5N1 vaccine shows promise in dairy calves and mice

Researchers at the University of Nebraska–Lincoln reported preclinical results for an experimental H5N1 vaccine that generated strong immune responses in mice and Holstein dairy calves, and fully protected vaccinated mice from lethal challenge with divergent H5N1 strains, including a 2024 bovine isolate from Ohio. The candidate uses a centralized consensus H5 antigen delivered in a prime-boost regimen with serotype-switched adenoviral vectors, given both intramuscularly and intranasally to try to build systemic and mucosal immunity. The findings are described in a forthcoming npj Vaccines paper and were highlighted by the university in late April. (news.unl.edu)

Why it matters: For veterinary professionals, this is an early but notable proof-of-concept at a time when H5N1 remains a cattle health, workforce health, and biosecurity concern. There are still no licensed H5N1 vaccines for cattle, and USDA’s response has centered on surveillance, including the National Milk Testing Strategy and mandatory testing tied to interstate movement of lactating dairy cattle. A vaccine that can reduce clinical disease, viral burden, and farm-to-farm spread could eventually become an important complement to testing and biosecurity, especially as H5N1 has now been confirmed in dairy herds across multiple states and continues to raise zoonotic concerns. (news.unl.edu)

What to watch: The next key step is whether these immunogenicity findings in calves translate into challenge-protection data in cattle, followed by regulatory and field-development work that would determine whether a bovine H5N1 vaccine can move toward real-world use. (nature.com)