The Texas health department reported 646 cases of measles in the state on Friday, an increase of 22 cases from three days ago, as the United States battles one of its worst outbreaks of the childhood disease.

As more counties are being impacted by the ongoing measles outbreak and added to the growing list of counties across Texas, here's what to know.

There have been 884 confirmed cases of measles across 30 states so far this year, according to the latest update from the CDC on Friday, far surpassing the 285 measles cases reported in the entirety of 2024 (the CDC does not provide data on how many cases are actively infectious).