In 2021 through the winter of 2022 Americans had already opened up their systems and so they were more like an open herd with people moving in and out and traveling. So, they ended up having a much more normal flu season with a strong fall peak around November, which is very normal and then their winter peak was slightly lower and longer than usual but it was much more like what we would normally see with the two peaks of influenza activity.
In Canada we had more of what we would consider a closed herd and we still had a lot of restrictions in place that limited movement in the country and internationally. So, we had a much lower and later single peak. As restrictions from COVID started to open up, we had much more movement of influenza viruses into and around Canada.
Dr. Detmer says, based on what happened in the United States last year where they were more open as we are now, we can expect a more normal, if not stronger influenza peak in the fall in Canada.
Source : Farmscape.ca