I suspect this increase in willingness to take vaccines is due to the increased spread of COVID—people looking for the light at the end of the tunnel. There will probably be a further increase as a result of i) the end of the election ii) positive vaccine trial results. https://twitter.com/GallupNews/status/1328686680551911425

I would be surprised if, at any point before say next September, there's an excess of vaccine because we can't find enough people willing to take it. (Maybe some oversupply at the local level, but I doubt nationally.) The challenge will be getting it in people's hands.

For posterity's sake, I suppose the caveat to the above is that I can imagine cases being on the decline again by March/April or whenever the vaccine becomes widely available, which could create a messaging challenge.