Porcine Reproductive and Respiratory Syndrome (PRRS) causes major economic losses, and cross-protection of Modified-Live Vaccines (MLV) against emerging heterologous strains remains uncertain. This study reports a field based, longitudinal before after intervention study evaluating the impact of a Lineage 7 PRRS MLV (PrimePac® PRRS) during an acute NADC-34 like PRRS outbreak in a commercial 1200-sow farrow-to-finish farm in South Korea. Following a confirmation of an NADC-34 like PRRSV outbreak, a whole-herd mass vaccination program was implemented using intradermal administration (0.2ml) of PrimePac® PRRS. Reproductive performance indicators (farrowing rate, abortions, stillbirths and mummification), vertical transmission dynamics (PRRSV qPCR testing of processing fluids), and post-weaning health outcomes (nursery and grow-finish morbidity and mortality, piglet viremia by qPCR) were monitored longitudinally before and after vaccination. After implementation of the vaccination program, key breeding-herd performance parameters progressively returned toward pre-outbreak baseline levels. PRRSV became undetectable in the processing fluid samples within one month, indicating rapid interruption of vertical transmission. Improvement in nursery and grow-finish pig performance occurred more gradually, consistent with ongoing virus circulation in a continuous-flow production system. This findings demonstrate that, although complete virus elimination was not achieved, a strategic mass vaccination program using a Lineage 7 PRRS MLV substantially mitigated the reproductive and early-life impacts of an NADC-34 like PRRS outbreak. Vaccination combined with biosecurity measures remains a critical component of integrated PRRS control strategies in farrow-to-finish systems where eradication is difficult.

Although the incidence of gastric cancer has been declining spontaneously and steadily for over 50 years, stomach cancer remains common. The World Health Organization’s 2020 annual report indicates a global incidence of gastric cancer estimated at 1,089,103 new cases per year, representing 5.6% of all cancers, with a mortality rate of approximately 768,793 deaths per year, accounting for 7.7% of all cancer deaths and ranking gastric cancer third in cancer mortality worldwide.