Isn't the target for everyone to have been offered vaccination by June? From what I've read, only a severe allergy to the ingredients in the vaccine make you not a candidate for having it.
I know each vaccine has different ingredients so maybe an allergy to one just rules out that one and you can have one of the others?? It's only a very small proportion of people who have these severe allergies. If the rest of the population has the vaccine then it cuts out any ethical issues about dividing the nation in two, passport holders and non-holders and also from the health aspect, means the non-holders are protected by the rest having had the vaccine.
If there's no reason not to get a vaccination other than allergy, then everyone will have been vaccinated at pretty much the same time and therefore all will hold a passport. Other than anti-vaxxers what am I missing?