Efficacy and safety of simultaneous vaccination with two modified live virus vaccines against porcine reproductive and respiratory syndrome virus types 1 and 2 in pigs.

•Double vaccination against PRRSV elicited responses comparable to single vaccination.•It is safe to administer two different MLV PRRSV vaccines were simultaneously.•The commercial PRRSV vaccines protected only against challenge with homologous strain.•Vaccination did not protect against challenge with a PRRSV-1, subtype 2 virus.