Did you ever wonder why it is that some people get the flu even when they’ve had a flu shot, while others seem to stay well even if they’ve never had a flu shot in their lives? To answer that question, researchers at the University of Michigan infected healthy people with the flu, and then observed what happened. According to MSNBC, they discovered that, first, only half of the study subjects came down with the flu and, second, that whether they got sick or not, everyone’s body was affected by the flu.
The difference, researchers said, was in the different ways the study subjects’ immune systems responded to the virus. The scientists then studied the subjects’ gene expression to see how their immune systems reacted to it, and found that everyone’s immune systems had “significant and complex” responses, even if they didn’t get sick. The key now, the researchers said, is to find out how the immune systems of those subjects who didn't get sick fought off the virus. The study was published in PLoS Genetics in August.