The spike in cases comes as some federal officials downplay measles and the importance of vaccination.
Arizona has seen 12 cases so far in 2026.
The South Carolina outbreak is now the largest in the country and will likely surpass the 762-case West Texas outbreak that began 1 year ago today.
Low coverage was seen in West Texas, southern New Mexico, northern Arizona, parts of Mississippi, and the rural Southeast.
Also, Utah has 25 new cases, raising the state total to 201.
South Carolina has reported 310 measles cases in the past 6 months.
The 2,144 confirmed US measles cases for all of 2025 reflect an increase of 79 infections.
South Carolina now has the same case count as Arizona, which confirmed 9 new infections today.
Of the total, 185 infections are tied to a growing outbreak in the Upstate region linked to elementary schools with low vaccination rates.
In another sign of growing vaccine hesitancy, a new report finds that the percentage of US toddlers vaccinated on time against measles, mumps and rubella has fallen since the COVID pandemic.
