We’ve heard it in the workplace or at school. We’ve said it to friends and co-workers.

“Don’t worry, I’m not contagious anymore.”

According to Internal Medicine Physician John E. Anderson, DO, Northwestern Medicine McHenry Hospital, common viruses and bacterial infections are contagious for longer than you think.

“Some viruses continue to shed, or replicate, long after symptoms have stopped,” says Dr. Anderson. “If you have a virus or bacterial infection, or are caring for someone with one of these illnesses, it’s important to wash your hands, be aware of what you’re touching, and avoid contact with others to prevent disease spread.”

A cough or a fever aren’t the only indications of being contagious. You’re contagious before you have symptoms — during the incubation period, when the virus enters your system.

And just because you feel better doesn’t mean those around you are safe. In fact, you’re still contagious after symptoms subside, carrying a bacterial or viral infection that can spread to others. So especially if you’ve had a recent illness, avoid physical contact with others, specifically children and the elderly, and avoid preparing food for others. Other habits that can help you avoid spreading germs: wash your hands frequently, avoid touching surfaces in public, and cover your mouth and nose when you cough or sneeze.

In addition to preventing the spread of germs, you can attempt to slow the spread of COVID-19 by contact tracing, identifying the people you've been in contact with who are infected. People with COVID-19 have a wide range of symptoms that appear within 2 – 14 days.

Here’s how long common viruses and bacterial infections are contagious.