Rob Keene, DVM, field veterinarian for Fort Dodge Animal Health, talked about the West Nile virus (WNV) vaccine at the West Nile Virus Workshop held March 7 at the University of Kentucky’s Gluck Equine Research Center. Keene explained plans for packaging and marketing the vaccine–which received a full license from the USDA on Feb. 6–and described the efforts already underway to combine the WNV antigen with others in future inoculations to be marketed.

Veterinarians will continue to sell the WNV vaccine (it will not be available over the counter). Fort Dodge will repackage the vaccine with the new full-license label and sell it in 50-dose quantities (they won’t be labeled for sale separately to clients). Fort Dodge will only sell the WNV (conditional and full license labeled) vaccine to veterinarians who maintain a doctor-patient-client relationship. The reason for the USDA’s strict repackaging law is possible illegal sale and distribution of the vaccine, which could mean improper use. Another reason to regulate the packaging and distribution is so that Fort Dodge can track where manufacturing lots of the vaccine were used.

The vaccine is labeled for the prevention of viremia (virus in the bloodstream), which it was proven to do in 94.6% of horses in the study (see article #3903 online). Control horses in the challenge study (the ones not receiving the vaccine) which developed viremia didn’t show clinical signs characteristic of WNV after being exposed to the virus. Nine out of 11 controls developed viremia, and only one out of 19 vaccinates developed viremia.

To give better perspective on the real-world results of the vaccine, Keene highlighted WNV field performance in North Dakota, Minnesota, and Oklahoma. Of the horses which died of WNV in those states, the mortality averaged 25%, and greater than 95% of the horses which died were not vaccinated properly with the initial shot, followed by a booster three weeks later. Many of the vaccinated horses which got sick were exposed early, before they were fully protected

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