3. Flu What it is: A viral infection of the nose, lungs, and throat. How you get it: When someone with the flu coughs, sneezes, or talks, droplets can spread up to 6 feet away. People get the virus from the air or by touching something the sick person touched and then touching their own nose or mouth. Why it’s serious: Up to 49,000 Americans die from the flu each year. The flu can create severe complications for people with asthma or diabetes.