According to the US Centers for Disease Control and Prevention, two doses of the MMR (measles, mumps and rubella) vaccine are 97% effective at preventing measles, while one dose is 93% effective. It is uncommon for someone who is fully vaccinated to develop measles, although the first breakthrough case of 2025 was recently detected in Colorado.

The number of measles cases in the U.S. has reached a 33-year record high, years after it was officially eliminated in the country, prompting public health experts to sound the alarm that other diseases could experience a similar resurgence.

Three deaths reported nationally as Ohio's outbreak ends with 35 cases, while Texas accounts for 753 infections in the largest national surge since measles was declared eliminated in 2000.

The US Centers for Disease Control and Prevention on Wednesday tallied the highest number of US measles cases since the disease was declared eliminated a quarter-century ago, just as a key Senate committee split the vote to advance President Donald Trump’s nominee to lead the public health agency.

The number of reported measles cases in the United States has hit 1,288 in the first six months of this year, the most since the disease was declared eliminated in 2000.

Halfway through 2025, the US’s total annual measles cases have reached a level not seen in more than three decades.