Reduction in finisher pig death rate on a farm in Japan following use of a commercial killed vaccine against porcine reproductive and respiratory syndrome virus

PRRS (Porcine Reproductive and Respiratory Syndrome) is a costly disease in the global pig industry. In 2021, Nisseiken Co., Ltd. in Japan launched a PRRS-killed vaccine, PRRS-ME, but its effectiveness on reducing the death rate under field conditions remained unassessed. A longitudinal study on a PRRS-positive farm in Japan (July 2019-July 2022) evaluated its effect on death rates. Piglets on a PRRS-negative farrowing farm were vaccinated at 3 and 8 weeks of age in March 2021. The vaccinated piglets were introduced to the finisher farm, where a PRRS outbreak occurred. Vaccination coverage was not associated with the death rates of growers but was negatively associated with those of finishers. The predicted reduction in the death rate of finishers associated with complete vaccination coverage was 56.8%.