The claim made by AstraZeneca / Oxford that the vaccine has 70% efficacy seems hard to justify given that figure was achieved by combining the results of 2 different dosing regimes one of which was a small subset containing no over 55s (90%) and the other a larger group which did contain over 55s (62%).

Surely the correct headline should be the vaccine has 62% efficacy but that further studies are to be carried out on a large representative population to see if the half dose then full dose regime does have greater efficacy.

Given the enormous political capital invested in this vaccine by the UK Government I wonder whether this has had the effect of pressurising AstraZeneca / Oxford to make a claim which at this point in time, according to some independent scientific opinion, does not appear to stand up to close scrutiny? A headline of 62% efficacy would not have looked great compared to the 95% efficacy claimed by the other 2 vaccines.