The U.S. Centers for Disease Control and Prevention is planning a large study into potential connections between vaccines and autism, two sources familiar with the matter told Reuters, despite extensive scientific research that has disproven or failed to find evidence of such links.

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.

Health and Human Services (HHS) officials led by Robert F. Kennedy Jr., recently confirmed that the Centers for Disease Control and Prevention (CDC) will investigate whether vaccines cause autism. The announcement reignited a longstanding debate over a theory lacking substantial scientific evidence.