Live Updates: Primaries Loom as Iran Presses for Concessions and Vaccine Debates Rage On

Live Updates: As primaries loom, Trump refines his rhetoric on the MMR vaccine and pushes an executive order to split it into separate shots; Iran links reopening the Strait of Hormuz to U.S. concessions such as compensation and sanctions relief, while Todd Blanche is sworn in as attorney general and other political and global headlines unfold.