Amid the measles outbreak, which is expected to “expand rapidly,” an expert explains how to stay protected from the virus

While most Americans may already be vaccinated against measles, some may benefit from the extra protection of a booster shot.

“Infected people are contagious from 4 days before the rash starts through 4 days afterward. The incubation period for measles, from exposure to fever, is usually about 7-10 days, and from exposure to rash onset is usually about 10-14 days (with a range of 7 to 21 days),” the CDC says.