One week ago today, I woke with a sore throat, stuffy nose, and aching head. Because I worried my bug could infect others, at 8:00 a.m., I dressed and slogged to a nearby walk-in clinic.

"Acute upper respiratory infection. It's caused by a virus," the doctor said as he removed stethoscopes from his ears. "Antibiotics won't kill a virus, so I won't be prescribing any. You'll be contagious for the next few days, so it's probably a good idea to stay home and rest."