Mass vaccination with modified-live PRRSV vaccine has no significant production impact in stable herds

Mass vaccination with a modified-live porcine reproductive and respiratory syndrome virus (PRRSV) vaccine has no significant negative impact on production performance in PRRSV-stable breeding herds, indicate the results of a recent study.

Investigators analyzed reproductive performance in eight PRRSV-stable breeding herds vaccinated with one of three commercial modified-live PRRSV vaccines (Ingelvac PRRS^® MLV, Ingelvac PRRS^® ATP or Fostera^® PRRS).  The herds were vaccinated quarterly for 2 years, totaling 64 herd mass vaccinations, and performance was evaluated based on five key performance indicators, each adjusted to per 1,000 sows:

• Number of abortions per week
• Weekly preweaning mortality
• Weekly prenatal losses
• Total pigs weaned per week
• Wean-to-first-service intervals

The scientists then used statistical process-control (SPC) methods to measure changes in production indicators, reported Sam Baker, VetMB, Columbia University’s Institute of Comparative Medicine, and Daniel Linhares, DVM, PhD, Iowa State University (ISU), at the 2017 ISU James D. McKean Swine Disease Conference. SPC methods involve the use of graphs to study how variation in processes change over time.

The investigators said the median interquartile range — a measure of data distribution — was 0.0 to 4.8 for increased abortions, 0.0 to 0.2 for prenatal losses, 0.0 to 8.0 for preweaning mortality, 0.0 to 0.0 for total pigs weaned and 0.0 to 0.0 for wean-to-first-service intervals, according to the results of the study, which was funded by the American Association of Swine Veterinarians Foundation.

They said the study will provide information to feed existing economic models that can help swine veterinarians make informed decisions about using modified-live PRRSV vaccines as a preventive tool.

They noted, however, that more research is needed to evaluate the first-time use of modified-live PRRSV vaccines in PRRSV-naïve farms to determine if it can minimize losses associated with outbreaks of wild-type PRRSV where the risk of introduction is high.

Ingelvac PRRS^® is a registered trademark of Boehringer Ingelheim Vetmedica. Fostera^® is a registered trademark of Zoetis Services LLC.