Looking forward, basic questions remain for 2021: How will essential workers at some risk (transit workers, teachers, grocery store employees) know when it’s their turn? (And it will matter which city you work in.) What about people with chronic illness — and then everyone else? And who administers the vaccine — doctors or the local drugstore?

In Belgium, where many hospitals and doctors are private but work within a significant central organization, residents will get an invitation letter “when it’s their turn.” In Britain, the National Joint Committee on Vaccination has settled on a priority list for vaccinations — those over 80, those who live or work in nursing homes, and health care workers at high risk. The National Health Service will let everyone else “know when it’s your turn to get the vaccine ” from the government-run health system.

In the United States, I dread a mad scramble — as in, “Did you hear the CVS on P Street got a shipment?” But this time, it’s not toilet paper.