Evaluation of internal farm biosecurity measures combined with sow vaccination to prevent influenza A virus infection in groups of due‑to‑wean pigs

Today we are sharing a new publication from the Torremorell’s lab regarding the impact that internal biosecurity measures can have on influenza A infection in piglets, when combined with sow vaccination. The article is available in open access on the Vet Research journal’s website.


  • Six Midwestern farrow-to-wean farms, positive for swine influenza. No vaccination in the six months prior.
  • Five farms used biosecurity measures and whole herd vaccination. One served as control.
  • Added internal biosecurity included stopping piglet movement after day 3 and no nurse sow and switching of equipment between litters for example.
  • All sows and gilts received two IM injections of a farm-specific autogenous influenza vaccine.
  • Thirty udder wipes were collected for three weeks (90 udder wipes total), starting six weeks after the second vaccination.
  • Environmental samples were collected each week as well.


  • No udder wipes and environment samples tested positive on 3 farms where vaccination+biosecurity measures were implemented.
  • One farm’s samples remained positive even after the intervention.
  • The control farm remained positive throughout the study.
Number (percentage) of influenza A virus rRT‑PCR positive litters before and after interventions measured by udder skin wipes by farm.

Read the article on the journal’s website.


Background: Influenza A virus (IAV) is an important respiratory pathogen of pigs that affects pig health, well‑being and productivity, has zoonotic potential, and has significant economic impact for producers. The ultimate goal is to maintain herds free from IAV. Due to the probability of IAV introduction into the herds, it is also desirable for herds to have some immunity to the virus. In this study, we evaluated a protocol that combined sow vaccination with the implementation of internal biosecurity practices during the pre‑weaning period with the goal to wean IAV negative pigs. Five IAV positive breeding herds were vaccinated twice, 3 weeks apart with a herd‑specific autogenous vaccine. For the subsequent 8 weeks, a biosecurity protocol was maintained, consisting of no pig movements after 3 days of age, no use of nurse sows, workers changing disposable gloves between litters, workers not stepping into farrowing crates, and daily disinfection of tools and materials used to handle pigs.

Results: Following these interventions, four of the five treatment farms had significant reductions in IAV detection (p value < 0.05). Three of the farms tested negative at all sampling points post‑intervention and one farm had a 21% reduction in IAV positivity.

Conclusions: This study indicates that a protocol that combines sow vaccination and enhanced biosecurity practices may limit IAV transmission among piglets and enable the weaning of groups of pigs free from the virus

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