“What we are seeing is pockets of intense anti-vaccine activity,” said Dr. Peter Hotez, a pediatrician and dean of the National School of Tropical Medicine at the Baylor College of Medicine in Waco, Texas. “A social movement of public health vaccine opposition has been growing in the United States in recent years. Subsequently, measles outbreaks have also increased.”

Experts believe that this is one reason why anti-vaccination hot spots like Clark County, Washington have popped up. But doctors and nurses say the recent outbreak is spurring people to get vaccinated. The Washington State Health Department says about 530 people were immunized against measles in January 2018. This January, there were more than 3,000 immunizations.

Since getting vaccinated is a medical procedure, in most cases teens younger than 18 need the consent of a parent, guardian, or other adult family member.