Project 458335

The flu leads to about 20,000 hospitalizations and 5,000 deaths per year in Canada - and up to 100 times more globally. We underappreciate that this is mostly due to heart disease complications. Evidence suggests that flu infection can increase inflammation and blood clots in the body, causing unstable plaques and blockages within days. Over time, this can lead to a risk of heart attack and stroke. Fortunately, studies have shown that flu vaccines can trigger the immune system to create antibodies that may be beneficial for the heart and blood vessels. Canada offers high- and standard-dose flu vaccines. Currently, the high-dose vaccine is approved for healthy older adults, but new research shows it can also be helpful for people with heart disease. Both groups have similar cellular processes that are also seen in other conditions, like cancer and diabetes. These processes do not often allow them to build a strong enough immune response with the standard-dose vaccine, leaving them vulnerable to the flu, further disease, and death. Since the high-dose vaccine appears to strengthen the immune response for these groups, it may further reduce heart disease complications. Sadly, few studies have compared flu infection complications in people with different medical conditions, often limited by small numbers and poorly identified infections. This proposal will use the latest statistical methods to study one of the largest groups of people who have tested positive in a lab for flu infection, to identify which medical conditions are at the highest risk, and what factors can predict multiple hospitalizations. Because our early research has already shown that flu vaccines may be equal to or better than heart disease medications, like blood pressure pills, we will also rank major flu vaccines to find which one best prevents complications. This research will fill an important gap in better preventing heart disease using flu vaccines as a low-cost and easily available strategy.