“CDC is not currently concerned that this will develop into a large, long-running outbreak," the agency said in December.

With 789 cases and counting, the current measles outbreak in South Carolina is now the nation’s largest since measles was officially eliminated in 2000. The highly contagious virus “is circulating in the community, increasing the risk of exposure and the risk of infection for those who are not immune due to vaccination or natural infection,” the state’s Department of Public Health says on its website.

Measles is spreading especially quickly among unvaccinated individuals—692 of the South Carolina cases are in unvaccinated individuals—just as it did in the large outbreak in Texas last year, which ultimately sickened 762, hospitalized 99, and killed two children.