How does any the flu spread?
It usually spreads from person to person in respiratory droplets when people who are infected cough or sneeze. People occasionally may become infected by touching something with influenza virus on it and then touching their mouth, nose, or eyes. Healthy adults may be able to infect others 1 day before getting symptoms and up to 5 days after getting sick. Therefore, it is possible to give somone the flu before you know you are sick as well as while you are sick.
