The US Department of Health and Human Services asked the US Centers for Disease Control and Prevention to study vaccines and autism, a person familiar with the situation told CNN, despite strong evidence that vaccines do not cause autism.

The CDC’s move comes amid one of the largest measles outbreaks the U.S. has seen in the past decade, with more than 200 cases and two deaths in Texas and New Mexico. The outbreak has been fueled by declining vaccination rates in parts of the United States where parents have been falsely persuaded that such shots do more harm than good.