Just telling you what my doctor and head nurse friends told me. They'll have to be readministered 2 doses, so they've wasted a lot of first ones on their staffs and themselves.
I think doctors/nurses are ethically bound to tell you what to expect (and it is the correct behaviour). I think they are right but they are not saying one thing: that 3rd dose will be a variant booster. Ie. it doesn't mean that 1st dose were a waste, don't think we know that yet.
Ie. most of the population will need either 3 doses (if they started early) or 2 doses of multivalent vaccines (upcoming)
Plus I fully expect newer multivalent vaccines by 2022, that we should all get.
The vaccination process will take at least 2 years and then we'll see if we've dealt with it or if we'll need yearly vaccines (like the Flu) - I am expecting that we'll deal with it as coronaviruses are generally not escape-artists.
We are just playing catch up to the virus at this point, but we'll soon get "ahead"of it (I don't mean literally ahead, I mean vaccines available at scale, in times to catch waves).