As discussed in this publication by Professor Jennifer Rogers last week, there have been discrepancies in the data reported by AstraZeneca in its trial of the coronavirus vaccine. Professor Rogers noted in particular: 

We are told that one dosing regimen (with a sample size of 2,741 participants) showed efficacy of 90 per cent when the ChAdOx1 nCOV19 vaccine was given as a half dose, followed by a full dose at least one month apart, and another dosing regimen (with a sample size of 8,895) showed 62 per cent efficacy when given as two full doses at least one month apart. The