Summary: Britain's approval Wednesday of Pfizer's COVID vaccine dialed up the anticipation, pressures and questions about vaccines in the U.S. and how the distribution will be handled. William Brangham spoke with Dr. Moncef Slaoui, chief scientific officer for the federal government's vaccine program, to learn more about the implementation of a vaccine. PBS NewsHour is supported by - https://www.pbs.org/newshour/about/funders
