I defer to any superior knowledge the Doc will offer in the coming days, luv2, but from what I gleaned from the news bulletins yesterday, I got the impression that they aren't "rushing through" the vaccine that Oxford University & Astra Zenica are working on.
Afaik, it's having to go through all the usual trial procedures that any new medication has to go through before being unleashed on us, albeit these are being carried out more urgently because of the effect of CV19.
And it's presently being held up simply because one of the trial group has had some sort of unusual reaction, which may, or may not be, specifically to the vaccine.