Of the three vaccines; 2 will require a 2nd shot. The third might but I haven’t read about it yet.
@muddy is correct. The 1st wave will be seeking the booster when the 2nd wave is starting to get in line.
Manufacturers are caught in the balance getting to maximum production as quickly as possible and planning for the time production can level out.
I’m envisioning mass immunization centers like we had in the early 1960’s for the polio vaccine. (I was little so I got a sugar cube dose) unfamiliar with this? It’s worth googling - polio in the USA has been eradicated thanks to the vaccine.
At some point bedside manner must take the back seat and the focus is “get it done”