titers based on the HI assay are not reflective of protection.
4. Discussion
In previously immunized horses, administration of a different commercial influenza vaccine containing a different sublineage clade stimulates equivalent HI antibody titers after one booster vaccination.
Acknowledgments
Funding Source Funding was provided by the Center for Equine Health at University of California, Davis.
Declaration of Ethics
The Authors have adhered to the Principles of Vet- erinary Medical Ethics of the AVMA.
Conflict of Interest The Authors have no conflicts of interest.