The first Americans could receive a Covid-19 vaccine as soon as 24 hours after the Food and Drugs Administration (FDA) grants approval, which would kick off the largest inoculation campaign in US history starting in mid-December.

“Within 24 hours from the approval, the vaccine will be moving and located in the areas where each state will have told us where they want the vaccine doses,” Dr Moncef Slaoui, the chief scientific adviser for the government’s “Operation Warp Speed” vaccine program, told NBC’s “Meet the Press”...