There are more viruses than stars in the universe, and luckily, most are harmless to us. But danger can come when we're exposed to a virus we’ve never encountered before.
Aired:
| Expires: | Runtime: 2m 53s
You are leaving GBH.org
You are leaving gbh.org and going to a web page that is not owned by GBH. If you are streaming, your experience will be interrupted.