Health authorities warned of further spread. Most U.S. measles cases this year involved people 19 and under and those without a confirmed vaccination.

According to the CDC, if you were born after 1957, one dose is considered sufficient to be considered protected from measles. Some adults may need a second dose. The CDC says adults who are going to be in high-risk settings for transmission should make sure they’ve had two doses at least 28 days apart.

Nearly 100 cases of measles have been reported across Texas and New Mexico. Measles was declared eliminated from the United States in 2000, making this outbreak a cause for concern. Health officials attribute the rise in cases to plummeting immunisation rates,