To clarify information released yesterday (Aug. 29) on two Kentucky horses which were reported to have been vaccinated yet contracteed
West Nile virus (WNV), the Kentucky State Veterinarian’s office noted that those two horses had not received their second dose of the
initial series of vaccine. Researchers and veterinarians don’t expect the vaccine to confer protection until about 20 days after the second
dose has been given, and it is recommended that there be a two- to four-week interval between the first shot and the second shot in the
initial series. Boosters should be given according to your veterinarian’s recommendations.

The two animals in question, one from Bourbon County and the other from Nelson County, had only received their initial vaccine. In both instances, the onset of clinical signs was observed prior to the animal having time to develop any immunity, noted Rusty Ford of the Kentucky State
Veterinarian’s office. He said the state veterinarian has full confidence in the vaccine. One of the horses was vaccinated Aug. 18
with symptoms developing that same day, and the second horses was vaccinated on Aug. 15 with symptoms first observed on Aug. 19.