Watch NPR’s video Flu Attack! How a Virus Invades Your Body and you’ll remember to sneeze into your elbow and wash your hands frequently!

When you get the flu, viruses turn your cells into tiny factories that help spread the disease. In this animation, NPR’s Robert Krulwich and medical animator David Bolinsky explain how a flu virus can trick a single cell into making a million more viruses.

CDC: Swine flu Cases Widespread and Rising