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When you — or your coworker or that lady on the bus — can transmit a cold or flu virus

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A flu virus
An influenza virus.
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We’re still in cold and flu season. And for weeks now at work, school, and on the bus, you might be wondering whether that person coughing over there is making us all sick.

“I always like to think about this from the perspective of a virus, and if you want to infect the most people — in other words, make the most copies of yourself, you're gonna hitch a ride when someone coughs or sneezes,” said Dr. Jon Hallberg, medical director of the University of Minnesota Physicians Mill City Clinic.

“That's obvious that someone might be contagious when that's going on. Unfortunately, with things like influenza and common cold viruses, you can actually be communicable — contagious — a day or two before you actually start having symptoms.”

How long you’re contagious depends on your body and the virus.

Hallberg offered timelines and best practices for keeping your germs to yourself in a conversation with MPR News host Tom Crann. Click play on the audio player above to hear it.