In an intense three-hour showdown, U.S. senators grilled Health Secretary Robert F. Kennedy Jr. on vaccine policy and his firing of the head of the Centers for Disease Control. Andrew Chang breaks down key moments in the heated exchanges between Kennedy and both Democrats and Republicans, and why he is facing increased scrutiny now in particular. 0:00 Intro 2:16 Promises & Lies 5:48 Chaos at the CDC »»» Subscribe to CBC News to watch more videos: http://bit.ly/1RreYWS Connect with CBC News