Measles is one of the more contagious respiratory diseases because it is transmitted through the air. The virus spreads through coughing and sneezing, and the tiny droplets can linger for up to two hours. That means you don’t even have to be near an infected person—just being in the same space where they coughed or sneezed earlier could put you at risk. It can also spread by touching contaminated surfaces and then touching your eyes, nose, or mouth. If someone has measles, 9 out of 10 people around them will likely get infected if they’re not already protected.

With measles and flu cases on the rise, it’s a good reminder to be mindful of how easily contagious diseases can spread—especially in places like schools, where people are in close contact every day. Washing your hands often with soap and water, covering your mouth when you cough, and staying home when you’re sick are simple ways to help prevent illness from spreading.