There was documented success using heterologous prime-boost vaccine strategies in controlling Influenza. Could we apply the same procedures/principles in PRRS?
In theory heterologous prime boost vaccination might also be beneficial in case of PRRSV. However, it has to be kept in mind that currently mainly modified live virus (MLV) vaccines are used to combat PRRSV, since current inactivated vaccines often lack sufficient efficacy. When using more than one MLV in the same herd, precautions must be put in place to prevent the formation of chimeras between different vaccine viruses.
The European medicines agency (EMA) recommends using not more than one vaccine virus strain within a herd and keep a withdrawal time, i.e. wait before introducing another MLV strain into the herd for as long as vaccinated animals might shed vaccine virus; this period is indicated by the manufacturer and varies between different PRRSV MLV products.
If you want to know more about PRRS vaccination read out chapter: Vaccinology
University of Veterinary Medicine, Vienna