() The number of measles cases across the United States is on the rise, and at least one person with the disease has died in Texas.

In Texas alone, the outbreak has grown to 124 cases across nine different counties. The Texas Department of State Health Services said 18 of those patients have been hospitalized. On Wednesday, the Associated Press reported that one person who had been hospitalized with measles died in West Texas. Their age wasn’t immediately made clear.

Five of those who have contracted measles were vaccinated, and the rest either were not vaccinated or their status was unknown, according to the department.

Texas health officials are saying this is the worst outbreak the state has seen in three decades.

The virus has also been reported in Alaska, California, Georgia, New Jersey, New Mexico, New York and Rhode Island.

The U.S. Centers for Disease Control and Prevention is providing technical assistance, laboratory support and vaccines as needed, the agency said.

What is measles?

Measles is an airborne disease caused by a virus that spreads when an infected person breathes, coughs or sneezes. It is highly contagious and can cause serious health complications, especially in children younger than 5 years old, the CDC says.

Symptoms include high fever, cough, runny nose, red, watery eyes or a rash.

Populations with high vaccination rates, above 95%, have herd immunity, meaning the disease is harder to spread, one pediatrician told .

“I don’t think there is a major concern that it’s going to be a pandemic like we saw in coronavirus,” said Dr. Joel “Gator” Warsh. “Most people are vaccinated or had measles, so the likelihood of it spreading in that way is pretty small. We’ve had many smaller-ish outbreaks in the last 10 or 20, years, and they generally don’t get huge.”

Newly confirmed Health and Human Services Secretary Robert F. Kennedy Jr. has not publicly spoken about the current measles outbreak. Kennedy has been branded a vaccine skeptic, and his positions have sparked concern, particularly due to a growing vaccine hesitancy in the U.S. following the COVID-19 pandemic. Kennedy’s supporters, however, say his positions only further the conversation about doing more long-term research on vaccines.

The Associated Press contributed to this report.