Because we don’t know how long post-Covid ‘natural immunity’ lasts (or how effective it is) or how long the Vaccine will last, if people have the vaccine the date of vaccination can be officially recorded and Doctors will then have a definite Immunity ‘starting date’.
Well said, Georgie. Just watched the minister holding forth in Commons about vaccine. Tucked away, in the hidden centre of a load of blather he said, words to effect of: “we don’t know how long [the vaccine’s] effects will last“. He did not elaborate on this but I suppose at least he told a little bit of truth.