Status of vaccines for porcine epidemic diarrhea virus in the United States and Canada.

In 2013, porcine epidemic diarrhea virus (PEDV) emerged in the United States as a rapidly spreading epidemic causing dramatic death losses in suckling piglets. Neonatal piglets are most vulnerable to clinical disease and their only protection is passive immunity from their dam. At the end of the third year of the PEDV outbreak, most US sow herds have been infected and many are entering into an endemic disease with much less, but still chronic losses. This endemic state and the occasional naïve herd that breaks with PEDV demonstrate a need to immunize sows to protect piglets. Stimulating PEDV immunity in the sow using safe and efficacious vaccines is the best course of action; however, conducting such studies to develop sow vaccines is very costly and logistically difficult. This manuscript reviews the status of PEDV vaccines available in the United States and Canada, and describes an experiment evaluating the potential use of young pigs as a surrogate model to evaluate potential sow vaccines.