South Carolina public health officials say hundreds of people are in isolation or quarantine amid a rapidly spreading measles outbreak in a northwestern region of the state with lower rates of vaccination. So far, 111 measles cases have been recorded, all but six of which occurred in unvaccinated people. Arizona and Utah are also experiencing a significant measles outbreak. Nationally, there have been almost 2,000 measles cases recorded in the United States this year, causing at least three deaths. The U.S. declared measles eliminated in the year 2000, but the disease has returned after vaccination rates fell during the COVID pandemic.