RFK Junior's handpicked CDC vaccine advisory panel is meeting right now as it considers more changes. They have already voted to not recommend the combined measles, MS, reubella, and chickenpox vaccine for kids under four, saying the chickenpox vaccine should be given separately. And today, the panel delayed a decision on the hepatitis B vaccine for newborns.Joining us now, NBC News national correspondent Aaron Gilchrist, who is at the CDC in Atlanta. Aaron, bring us up to speed. >> So Katie, I'll tell you ...