Infection dynamics of Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) in vaccinated and non-vaccinated pigs

Piglets from a PRRSV (EU type) seropositive stabile sow herd were seronegative at weaning, but became infected with PRRSV EU after transfer to the finishing units located at the same site. To control PRRSV among the finishing pigs, vaccination with a modified live virus PRRSV EU vaccine (Intervac PRRS) all pigs prior to transfer to the finishing stables were initiated from October 2008. In July 2009 it was decided to terminate vaccination of pigs at transfer.   The aim of this study was to