Democratic Representative Adam Schiff sent a letter to Google Chief Executive Officer Sundar Pichai and Facebook founder Mark Zuckerberg, expressing concern that their platforms are carrying information discouraging parents from vaccinating their children.

"I am requesting additional information on the steps that you currently take to provide medically accurate information on vaccinations to your users," Schiff said in an emailed statement. "I was pleased to see YouTube's recent announcement that it will no longer recommend videos that violate its community guidelines, such as conspiracy theories or medically inaccurate videos, and encourage further action to be taken related to vaccine misinformation."

Schiff is chairman of the House Intelligence Committee.