All the more reasons to stay healthy. I had a medical Dr. tell me in the mid 1980's, EVERYONE should be at least 15-20 pounds heavier, then the stats for your height and weight BECAUSE if you are at your normal weight or thinner, a kick-A$$ flu / virus could really throw you for a loop.
He went on to say that some flu bugs lay you up for weeks, you lose weight, and those extra 15-20 lbs. could be the difference between getting healthy faster or getting sicker.
Healthy lifestyle, good drinking water too helps keep the body more resistant. So does avoiding crowded stores with sneezing coughing people. Try shopping at off peak hours.