With the elevated risk of contracting measles, some people are now wondering if their vaccines are working to protect them from this contagious virus -- or if they need another vaccination on top of the shots they may have already gotten.

“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.