As a measles outbreak in Texas has grown to nearly 150 cases, US Health and Human Services Sec. Robert F. Kennedy Jr. said in an opinion piece on Fox News on Sunday that parents should consult with health-care providers “to understand their options to get the MMR vaccine” for their children.

Measles are spreading and have already caused one death. Here's what you need to know according to the CDC and medical experts.

Health experts say there ought to be no outbreaks in the United States. “Each outbreak signifies a lapse in our public health defenses and poses serious risks, especially to children,” said Dr. Jerome Adams, who served as U.S. Surgeon General during the first Trump administration.

Before the measles vaccine, there were over 30 million cases of the disease worldwide each year.

Measles is highly contagious. Without a vaccine, 9 out of 10 people exposed to measles will become infected, the CDC said. About 1 to 3 of every 1,000 children with measles will die, usually from pneumonia or neurologic complications.

Los Angeles County has its first confirmed case of the measles amid a growing number of cases in the United States.

Public health experts said that although it’s true we have measles cases in the U.S. every year, the latest outbreak is concerning.