Information on the use of attenuated PRRSV live vaccines
CVMP recommendation on the use of live attenuated PRRSV vaccines
The CVMP is aware of a recombination event between two live attenuated Porcine Reproductive and Respiratory Syndrome virus (PRRSV) type 1 vaccine strains leading to a recombinant strain that has been associated with clinical signs of disease in PRRS-naïve herds in Denmark.
Recombination between strains of PRRS virus, including live type 1 PRRSV vaccine strains, is a known phenomenon that has been reported in the scientific literature. Therefore, recombinations of PRRSV strains similar to the one observed in Denmark may occur elsewhere at any time.
The CVMP makes the following recommendations concerning the use of live attenuated PRRSV vaccines:
In order to limit the potential risk of recombination between vaccine strains, the simultaneous or consecutive use of different live attenuated PRRSV vaccines should be avoided as much as possible while continuing to protect animal health.
Increased monitoring of any suspected adverse event relating to clinical signs of PRRS, including the occurrence of relevant clinical signs of the disease in vaccinated herds, is recommended. Any suspected adverse event should be reported to the national competent authority for veterinary medicines or the marketing authorisation holder. Clinical signs of PRRS include reduced fertility, increased rate of abortions, reduced appetite, increased piglet mortality and respiratory distress.
It should be noted that sequence data indicating recombination between vaccine strains or between vaccine strains and wild types should be regarded as relevant pharmacovigilance data and therefore should be reported.