Canadian and Nebraska Research Teams Advance H5N1 Cattle Vaccine Science as Herd Immunity Data Surprises Scientists

Two North American research programmes are building a scientific foundation for bovine H5N1 vaccination, with Canadian findings revealing unexpectedly strong post-infection immune responses in dairy cattle while University of Nebraska-Lincoln researchers report broad preclinical protection in calves — against a backdrop of more than 166 million US poultry birds culled and no licensed cattle vaccine yet available.e.

New Canadian research from VIDO-InterVac in Saskatoon is reshaping understanding of how dairy cattle respond to highly pathogenic H5N1 infection. Dr Antonio Facciuolo’s team infected lactating cows under high-containment conditions and found immune responses that were, in his words, “quite surprising” — robust enough to reduce the risk of reinfection. Complementary findings from Ohio State reinforce the picture. While infected animals still suffer significant consequences — mastitis, steep milk output declines, lasting mammary tissue damage and post-recovery culling — VIDO found cows recovering to approximately 70% of previous production during the study. A haemagglutinin-based mRNA vaccine reported on PubMed was well tolerated in lactating cows and generated strong, durable antibody responses, pointing toward a viable vaccine pathway.

At the University of Nebraska-Lincoln, Eric Weaver’s team has developed a vaccine platform targeting multiple H5N1 strains and stimulating immunity in both the bloodstream and respiratory tract. Tested in mice and dairy calves, the platform delivered complete protection against severe disease in preclinical trials. Calves received intramuscular and intranasal doses at one week of age, followed by a booster at five weeks. Weaver is now seeking funding and partners to advance the work toward licensing.

The urgency is clear. H5N1 has spread to dairy cattle across the United States since 2024, with approximately 70 farm workers reported ill following close contact with infected animals. Currently, no licensed H5N1 cattle vaccine exists anywhere in the world.