Merck Prestige WNV has been shown to be effective for the vaccination of healthy horses 6 months of age or older against West Nile Virus. Duration of immunity has not been established. For more information regarding safety and efficacy data, go to productdata.aphis.usda.gov. This product has been shown to be effective against encephalitis and viremia caused by West Nile Virus.
For primary vaccination aseptically administer 1 mL intramuscularly, repeat with a single dose in 3 – 4 weeks. Historically, annual revaccination with this product has been recommended. The need for this booster has not been established. The presence of maternal antibody is known to interfere with the development of active immunity in foals and additional boosters will be required in most young animals. For more information on revaccination frequency, consult your veterinarian.