WNV vaccine safety

Viewpoint WNV Vaccine Safety Over the course of the past few weeks, news articles and Internet rumors have surfaced regarding the West Nile-Innovator vaccine, the United States Department of Agriculture (USDA)-approved vaccine for protecting horses against West Nile virus. The rumors and misinformation pertain specifically to abortions and deformed foals after vaccination for West Nile virus. An article published in the Denver Post on May 30, 2003, has served to intensify the spread of inaccurate and misleading information on this critically important matter. As a result, Fort Dodge Animal Health, manufacturer of the West Nile-Innovator vaccine, would like to set the record straight regarding the safety and efficacy of this vaccine. • The USDA Center for Veterinary Biologics is not considering any market intervention against the West Nile-Innovator vaccine, contrary to the implication in the Denver Post article. Many comments by the USDA official in the article were taken out of context and are inconsistent with the Department’s official position on the vaccine. • Although the USDA is aware of a few reports of abortions after use of the vaccine in pregnant mares, the Department’s official recommendation for prevention of West Nile virus still includes vaccination, as outlined on their website, at www.aphis.usda.gov/oa/pubs/adalahwnv.html. • Millions of doses of the vaccine have been used since it was approved in 2001. The vaccine is field-tested and proven with an excellent safety profile. • The Denver Post reported that, during the safety trial for the vaccine, “at least five mares lost pregnancies or had stillborn fetuses.” This is untrue. One 22-year-old mare was diagnosed to be pregnant by an ultrasound examination and after two doses of the vaccine was found to be “open.” The veterinarian in charge of the mare declared in his official report that this early embryonic death was “unrelated to the vaccination.” There were no other problems with pregnant mares receiving the vaccine in the study.

• The Denver Post article lacks credible evidence to support its conclusion. The circumstances of the reported abortions are unclear and lack veterinary involvement and/or confirmation. • More than 15,000 horses have contracted West Nile virus since it was first documented in this country. About one third of those animals died. The West Nile-Innovator vaccine is a safe and proven way to prevent this deadly disease. Fort Dodge Animal Health knows you are aware that West Nile virus poses a major health threat to the horse population, and that maintaining a high level of protection has emerged as the top priority among equine practitioners. This communication is provided to you as background information should this topic come up during your editorial meetings, or if you receive a Letter to the Editor submission that perpetuates any of the rumors or untruths about the West Nile virus vaccine. We know that Journal of Equine Veterinary Science is a highly reputable publication, and that you and your staff want complete and accurate information. Please contact Fort Dodge Animal Health at 1-800-533-8536 if you have any questions regarding this letter or need further information on the safety or efficacy of West Nile-Innovator. Thank you for your attention on this very important matter. Stephen A. Connell, DVM

From Fort Dodge Professional and Technical Services Copyright © 2003, Elsevier Inc. All rights reserved 0737-0806/03/2310-0003 $30.00/0 doi:10.1053/jevs.2003.124

Volume 23, Number 10

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