Iowa veterinarian sees benefits to early PRRS vaccination

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It takes 3 to 4 weeks for pigs to develop immunity against porcine reproductive and respiratory syndrome virus (PRRSV) after vaccination with a modified-live vaccine, so vaccinating early gives them the time they need to develop immunity by nursery age, according to Keith Aljets, DVM, Veterinary Medical Center, Williamsburg, Iowa.

“We are concerned more about the effects of PRRSV earlier in life,” versus later in life, he told Pig Health Today.

At the 2017 American Association of Swine Veterinarians, Aljets described a vaccinated sow herd in his practice that had been “leaking” wild-type PRRS virus into suckling piglets and causing mortality in the nursery. The situation indicated a need to stabilize whole-herd immunity, he said.

Aljets then conducted an independent trial on a farm with 2,800 sows that sends weaned pigs to 10 nursery sites in Iowa. The sow farm was not “overly clinical” to PRRS virus, he said, but he was concerned about the presence of wild-type PRRS virus in the weaned pigs.

Alternating modified-live vaccines, they vaccinated sows every quarter with the goal of “providing more stability and minimizing the leakage downstream” of resident, wild-type PRRS virus, Aljets said. He then vaccinated all piglets with Fostera PRRS at 3 to 5 days of age, although the vaccine may be used at day 1.

The veterinarian was initially concerned that using a modified-live vaccine in very young pigs would disrupt piglet health. Instead, “we saw continued improvement in mortality” and have continued to use the vaccine, he reported.

In addition, there was no reported negative impact on sow reproduction after the use of Fostera PRRS was initiated, Aljets added.