It’s officially fall, which means crisp air, cozy sweaters, autumn leaves ― and a fresh wave of colds and flu.

“It’s almost inevitable that we will come into contact with at least one of the common respiratory viruses each cold and flu season,” Dr. Andrew Fleming, section chief of infectious diseases and immunology at New York University Langone Brooklyn, told HuffPost. “A well-maintained immune system can halt these viruses before an infection sets in.”

Between the unpleasant symptoms and schedule disruption, getting sick is hardly anyone’s idea of a good time. That’s why it’s crucial to do what you can to prevent the spread of germs, strengthen your body’s defenses and otherwise decrease your risk of infection.

“While most people who get a cold or the flu ultimately do just fine, these illnesses can be deadly to others,” said Dr. Carrie Horn, the chief medical officer at National Jewish Health. “And sometimes even otherwise young and healthy people can develop complications from a simple cold like pneumonia that could become serious.”

With that in mind, acting with awareness about illness isn’t just about protecting yourself, but also protecting your community. In fact, it’s a matter of etiquette.