Safety of Porcilis PRRS in sows

Porcilis PRRS is registered for the use in piglets from 2 weeks of age, gilts and sows. Intervet has performed a number of experiments to test the safety of its vaccine in sows

The most sensitive safety test was an experiment in which complete PRRS naïve sows were vaccinated with a normal dose of Porcilis PRRS at the end of gestation, the most critical period in terms of adverse side effects. In a small proportion of the animals there was some viral transmission to a number of piglets. No clinical disease was detected in the sows or piglets. We know from literature and from our own experiments that virus transmission to piglets in late gestation may occur with all live PRRSV vaccines.

Since PRRS is important in sows as well as in fatteners, some farmers and veterinarians are keen to vaccinate adult animals too. Sows are often vaccinated during lactation or at random at 4 month intervals and gilts before insemination. Intervet is of the opinion that the use of live vaccines in sows should usually be restricted to farms where the presence of the PRRS virus has been demonstrated by serological investigation. Only in very rare cases, vaccination might be advised on a PRRS-negative farm, e.g. a newly built farm in a PRRS-positive area where infection is foreseen in the next few months. In those circumstances the use of a live PRRS-vaccine should be carefully considered.