In case there's confusion from the weekend's communications (and I'm thinking back to the 15 Feb 2020 target to offer a first dose to all those in JCVI Groups 1-4), the 'booster' target has been brought forward by one month.
I have seen this mis-reported as 'everyone over 18 to get a jab by the New Year.
The previous target was to offer a booster dose to all over 18s (in England but other home nations expected to do the same) by end Jan. This implies a vaccination appointment within 28 days (of 31 Jan).
The new target is to offer a booster dose to all over 18s by NYE, implying a vaccination appointment by end Jan.
Whereas the previous version was entirely 'doable' this is going to be a massive ask: I hope that the effort will be balanced against the need to keep all the other parts of the NHS going full tilt. Still better than lock downs and the adverse effect on people's educational and mental well-being.
The average daily vaccination rate will need to be about 650k per day (averaged over the 48 days and taking into account down time during seasonal holidays). The rolling average is currently 458kpd.
Current totals are: first 51M, second 47M and booster 23M.
There's still a dribble (50+k per day) of first and second jabs including those for adolescents, but this rate will trend up.
There are still 4M who 'need' a second dose. I suspect jabs for 5-11s (5M) will be placed on hold till Feb half term, if the JCVI decide to recommend that the programme extends to that age cohort.