As of July 24, 2026, the U.S. Centers for Disease Control and Prevention (CDC) reported 2,318 cases of measles, surpassing the total of 2,289 cases recorded in 2025. This marks the highest number of cases since 1991, with significant outbreaks occurring in South Carolina, Utah, and Arizona. The CDC notes that vaccination rates have fallen below the 95% threshold necessary to prevent outbreaks, which has contributed to the increase in cases.
Public health officials acknowledge that the actual number of cases may be higher than reported due to undercounting, as some individuals do not seek treatment. For example, in Utah, over 700 cases have been reported, and experts suggest that the outbreak could be three to four times larger than currently known. In South Carolina, the state's health department indicated that the 997 cases reported may also be an undercount.
In Texas, researchers are still assessing the 2025 outbreak, which initially reported 762 cases, with early findings suggesting that the actual number may be nearly double that figure. The CDC defines an outbreak as three or more linked cases, but low vaccination rates and limited disease surveillance can lead to underreporting. Experts emphasize the importance of maintaining high vaccination coverage to protect vulnerable populations.