There are serious signs the FDA is getting cold feet over the notion of issuing emergency use authorizations to allow for the widespread early deployment of Covid-19 vaccines. Instead, it appears the agency may be exploring the idea of using expanded access — a more limited program that is typically used for investigational drugs — in the early days of Covid vaccine rollouts. Whereas a few weeks ago the agency’s concern was to protect against the possibility that unproven vaccines would be pushed out prematurely due to pressure from President Trump, now the fear is that early authorization of vaccines could squander a one-time chance to determine how well the various vaccines work and which work best in whom.