Flu viruses are spread by contact with droplets sneezed or coughed from an infected person. Breathing in the droplets or aerosols (very small particles in the air) containing flu viruses is the most common way to get the flu. Touching contaminated objects on which droplets have landed also infects many people. Flu viruses can also spread by direct contact with each other, such as by shaking hands or hugging. You can spread the virus to others before you feel sick yourself. The CDC says you are contagious a day before symptoms start and up to 5 days afterward.
You can protect yourself against the flu by doing simple things like washing your hands before eating, not putting your hands near your face or in your mouth, and wearing a mask over your nose and mouth when around others. Washing hands for at least 20 seconds with soap and clean, running water works well. If soap and water are not available, rub your hands with an alcohol-based hand cleaner that contains at least 60% alcohol. If someone in your family has the flu, you can help prevent it from spreading by wearing a mask and by cleaning surfaces with a solution of 1 tablespoon of bleach to 1 gallon of water.