More than 100 cases of the measles are impacting states across the country, including Missouri, Kansas and Oklahoma.
The C.D.C. has confirmed at least 107 cases in the U.S. so far this year.
In 2017 there were 118 cases all year.
Measles was eliminated in the U.S. In 2000, but outbreaks have been confirmed nearly every year since.
Officials say the majority of people infected are unvaccinated.
International travelers often bring the disease into the country.
It’s spread through the air when someone coughs or sneezes and causes fever, cough, runny rose, red eyes, and rashes of red spots.
The C.D.C. recommends people avoid the illness by getting vaccinated with an MMR Vaccine.