Vaccination of influenza a virus decreases transmission rates in pigs

Romagosa, Anna; Allerson, Matt; Gramer, Marie; Joo, Han Soo; Deen, John; Detmer, Susan; Torremorell, Montserrat

All seeder pigs were RT-PCR positive at 48 h post inoculation and prior to comingling with the contact susceptible pigs. At that time point, the virus titers from nasal swabs in those pigs ranged from 3 × 10 2 to 1 × 10 5 TCDI 50 /mL. All the contact pigs (100%) in the NV group were found RT-PCR positive by 5 dpc, while in the vaccinated groups, 15 out of 40 pigs (37.5%) in the HE group and none of the pigs (0%) in the HO group were positive by RT-PCR (Table 3) . Comparison of the cumulative percentages of contact pigs infected per day between treatment groups via the log-Rank test from the Kaplan-Meier survival analysis indicated that the percentage of infected pigs was significantly higher in the NV group than in the vaccinated groups (p < 0.0001), and the distributions did not overlap between 90% confidence intervals ( Figure 2 ).