American health officials report that more than 700 people have been infected by measles this year, marking a 25-year high for the infectious disease.
The Centers for Disease Control and Prevention said on Monday that cases had been recorded in 22 states and were mostly affecting unvaccinated children.
Officials said the increase in cases is the largest since 1994, including 78 reported in the past week. There have been no deaths reported as a result of the outbreak.
“The suffering we are seeing today is completely avoidable,” US Health and Human Services Secretary Alex Azar said on Monday.
Mr Azar directed his comments at some parents who have chosen to leave their children unvaccinated due to the unscientific claim that vaccines cause illnesses such as autism.