Effect of vaccination route (intradermal vs. intramuscular) against porcine reproductive and respiratory syndrome using a modified live vaccine on systemic and mucosal immune response and virus transmission in pigs.

Our results show that the tested MLV1 induced a faster cell-mediated immune response after ID immunization two weeks after vaccination but was equally efficacious after IM or ID immunization towards a challenge four weeks later. Considering the practical and welfare benefits of ID vaccination, these data further support the use of this route for PRRS MLVs.