Health and Human Services Secretary Robert F. Kennedy Jr. faced tough questions on Capitol Hill from senators amid turmoil at the CDC and controversial changes to government vaccine policies. Senator Ron Wyden (D-OR) got into a hostile back and forth with the HHS Secretary after Wyden said he's been sent letters of concern by doctors and scientists over Kennedy’s actions so far in office. Our next MSNBC Live event is on October 11th in New York City! Buy Tickets now: msnbc.com/live25 For more