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 Infectious Diseases Society of America (IDSA) issued a statement in response to the news of the CDC’s potential study. The group emphasized the proven safety of vaccines and expressed concerns at the diversion of federal research funding from more crucial areas of study, including unknown causes of autism.