Even healthy people are at risk, but those with heart failure should take particular note of today's news.
"It is well known that influenza infection is associated with increased risk for mortality in heart failure patients," said Dr. Hidekatsu Fukuta, the lead author of the new study, a cardiologist at Nagoya City University Graduate School of Medical Sciences in Japan.
Fukuta lead a study that looked at people with heart failure who had received the flu vaccine. In the study, set to be presented at the American College of Cardiology meeting, the heart failure patients who received the flu vaccine in any given year showed a 50 percent decrease in risk of death during flu season, as well as a 20 percent decrease for the rest of the year.
About 6.5 million Americans live with heart failure, which means their hearts aren't strong enough to effectively pump blood through their bodies. And they may be more susceptible to complications from the flu, including pneumonia, and of course, the stress on their body from the flu could worsen their heart problems.
This study, an analysis of six past works on heart failure and flu that included more than 78,000 patients, found that the proportion of heart failure patients who had gotten the flu vaccine ranged from 26 percent to 86 percent.
Researchers did caution that while the observational studies they used to collect the data mean that getting a flu vaccine is associated with fewer deaths, it doesn't necessarily prove cause and effect the way a randomized controlled study would.
Because Fukata's study will be presented at a cardiology meeting, it hasn't yet been through the rigorous peer review that's required to get new medical research published in a medical journal and the study itself hasn't been released.
But Fukuta says that this may give heart failure patients an extra, and new, motivation to get the flu shot, which is widely available and inexpensive.
Jay-Sheree Allen, M.D. is a resident in the ABC News Medical Unit.