Veterinary Information on the Use of Porcine Reproductive and Respiratory Syndrome (PRRS) Vaccines

The Paul-Ehrlich-Institut (PEI), the Federal Institute for Vaccines and Biomedicines, has been informed of an outbreak in Denmark involving Porcine Reproductive and Respiratory Syndrome (PRRS). This outbreak was caused by a recombinant PRRS virus strain. It is believed that this results from the recombination of vaccine virus strains of two live PRRS vaccines. Further investigations are still pending.

Recombination between PRRS virus strains including type 1 PRRSV vaccine strains is a known phenomenon mentioned in scientific literature. Therefore, recombinations of PRRS virus strains, similar to those observed in Denmark, can occur anytime and anywhere. As live attenuated vaccines are an important tool to combat PRRS, the Committee for Veterinary Medicinal Products (CVMP) at the European Medicines Agency (EMA) has developed guidance for all users of live PRRS vaccines. The guidance is published in the press release of the last CVMP meeting.

Instructions for Action

• In order to minimise the potential risk of recombination between PRRSV vaccine strains, simultaneous or sequential use of different live attenuated PRRS vaccines should be avoided as far as possible, while ensuring animal health protection.
• The Paul-Ehrlich-Institut reminds all users to report any cases of side effects or suspected indications of poor efficacy of these vaccines to the respective marketing authorisation holder or to send them directly to the Paul-Ehrlich-Institut via the online registration form.
• Virus sequence data indicating a recombination between vaccine virus strains or between vaccine virus strains and wild virus types should also be reported.

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