Kevin Vilaca from South West Ontario Veterinary Services, Sow Herd Flu Vaccine Shows Promise

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The clinical effects of Influenza Type A (IAV) on the pig’s respiratory system are well known. Reproductive failure due to infection with influenza A viruses has been described in the literature. The effect of IAV on the metrics of reproduction are less well defined and have been more difficult to reproduce experimentally.  These German researchers designed a longitudinal field study that would compare the reproductive performance parameters before and after the implementation of vaccination against the influenza A (H1N1)pdm09 virus in sow herds that were already endemically infected with pandemic influenza A virus. This study involved 137 sow herds in Germany with a total of 60,153 sows. Average reproductive performance parameters such as return to estrus rate, abortion rate, stillbirth rate, number of piglets born alive per litter, pre-weaning mortality rate and number of piglets weaned per sow per year were recorded for 6 months before vaccination and 6 months after completion of primary vaccination.
The researchers found the following:

  • 79.8% of the farms experienced reduced reproductive performance when clinical signs of Influenza A were present in the endemically infected herd.
  • After immunizaton for Influenza A (H1N1) pdm09 there was a significant decline in the return to oestrus rate (p < 0.001), abortion rate (p < 0.001) and pre-weaning mortality rate (p = 0.023)
    as well as a significant increase of the number in piglets born alive (p = 0.001) and piglets weaned per sow per year (p < 0.001) . The stillbirth rate did not change significantly.

Take Home Messages:

  • This study suggests that by vaccinating against the influenza A (H1N1)pdm09 virus, an improvement in reproductive performance can be achieved in sow herds already endemically infected with influenza A (H1N1)pdm09 virus .
  • Although this is a longitudinal study over time the numbers of herds involved seems to support the clinical and production impression that Influenza A negatively affects reproductive performance. Hopefully an improved controlled experimental model can confirm these interesting findings in the future.
  • Broadening the vaccine coverage to a group of IAV isolates that is representative of IAV found within a “region” would provide broader protection for covering a wider range of IAV types that could affect susceptible sow herds.

Ref:   Gumbert S, Froehlich S, Rieger A, Stadler J, Ritzmann M, Zoels S.   Reproductive performance of pandemic influenza A virus infected sow herds before and after implementation of a vaccine against the influenza A (H1N1)pdm09 virus.  Porcine Health Manag. 2020 Jan 23;6:4. doi: 10.1186/s40813-019-0141-x. eCollection 2020.

Submitted by Dr. Kevin Vilaca

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