Comparative Efficacy of Vaccines

Several researchers have been working the past few years to determine if any U.S.-registered equine vaccine had advantages over others. It turns out that the serologic responses to–and protection given by–these vaccines varies significantly. Hugh G. G. Townsend, DVM, MSc, of the Department of Large Animal Clinical Sciences at the Western College of Veterinary Medicine in Saskatoon, Saskatchewan, presented results of the comparative study.

The scientists looked at seven killed vaccines and one modified-live vaccine produced by major U.S. manufacturers. Fifty naìve nine-month-old horses were used in the study. Blood samples were taken every four weeks to measure serologic response to influenza, tetanus, and equine herpesvirus (EHV) vaccines until they were challenged with equine influenza virus (EIV).

The following vaccines were used: Intervet's Encevac T (Eastern and Western equine encephalitis, or EEE and WEE, and tetanus) and Prestige II (EHV types-1 and -4, and EIV); Fort Dodge Animal Health's (FDAH) Equiloid (EEE, WEE, tetanus) and Fluvac EHV-4/1 Plus (EIV, EHV-1 and -4); Boehringer Ingelheim's (B-I) Cephalovac EWT (EEE, WEE, and tetanus), Calvenza EHV (EHV-1), and Calvenza EIV; and Intervet's Flu Avert (EIV modified-live vaccine) in combination with Encevac T and Prestige II