Swine Barn Workers Encouraged to Get Their Flu Vaccine and Protect Pigs

By Harry Siemens

Dr.

With the further relaxation of restrictions in Canada patterns of influenza infection will return to more normal this year, as in the United States last year.

Dr. Detmer said with the lockdown and pandemic precautions, few influenza viruses circulated in humans in the northern hemisphere, including Canada, Europe, and the US. From 2021 through winter 2022, Americans opened up making it more like an open herd for people travelling with limited restrictions. It created a normal flu season with a strong fall peak around November. And then their winter peak was slightly lower and longer than usual; normally seen with the two peaks of influenza activity.

In Canada, producers had more of a closed herd with limited movement in the country and internationally, producing a much lower and later single peak as restrictions from COVID started to open up. But unfortunately, that’s when the movement of influenza viruses increased in Canada, explained Dr. Detmer.

The key drivers of the respiratory virus circulation are for the most part aerosol but also close contact transmission. In-person gatherings are one way these viruses spread within the community, and air travel is how they move between communities. They also travel on land, but the big one is air travel she noted.

“People travelling a long distance introduce a virus that is not necessarily in that population,” said Dr. Detmer. By April, Canada had lifted most of the restrictions and in early fall removed most of those remaining border restrictions.

She said for the first time in a very long time the industry has the best chance of the vaccine matching to what is circulating in the population compared to last year when experts had a 50/50 shot. Last year there were two H3N2 virus strains to choose from and the wrong one to vaccinate against was picked.

“It’s in the vaccine and 70 to 80 percent of what’s circulating this fall is that H3N2 a good match,” said Dr. Detmer. “The H1N1 is at least 20 per cent of what’s circulating; is the derivative or the evolution of the 2009 pandemic, H1N1.”

She said that H1N1 is still circulating in the human population and the Yamagata lineage Influenza B is in the current influenza vaccine giving good coverage this year.

Dr. Detmer said before the COVID pandemic that the H1N1 virus from the 2009 pandemic was a seasonal strain of flu in humans.

“Every year we saw it and every year as a pig influenza surveillance person, I saw that pandemic strain get into pigs every year,” she said.

Even now the circulating H1N1 in pigs is from years ago, although almost half of what she sees annually comes directly from people into pigs. Last winter, the humanto-pig transmission was the most common H1N1 which is one of Quebec’s pigs’ most detected genetic strains. Dr. Detmer predicts the same occurrences will happen repeat this year.

Since pigs have that pandemic-like H1N1 virus circulating and humans are also susceptible to the virus and circulating it, getting the annual flu vaccine protects people from getting serious infections with the strain.

“It helps break the human-to-pig-to-human-to-pig cycle that shows where the virus goes back and forth between the two populations,” she said. “So for that reason, I recommend you get your flu vaccine and help protect both the human and your pig herd.”