This year, 21 people in Orange County have been diagnosed with the highly contagious respiratory disease and seven have been hospitalized. In a typical year, Orange County has no reported cases of measles.
The Orange County Health Department held an emergency meeting Tuesday night to discuss the unexpected outbreak and encourage residents to get vaccinated. The vaccine is 99 percent effective after two doses.
Neighboring counties, such as Riverside and Los Angeles, have also seen a spike in cases.