Risks not only the vaccine supply chain but the entire trade treaty falling apart.
It will back down, of course. It is embarrassing to be seen to be incompetent. But no one can say that needing to order vaccine wasn't immediately obvious. And they dawdled. So they are paying the price.
No one hijacked the AZ vaccine. The UK simply approved and ordered it before the EU, set up manufacturing facilities and focussed on building an army of vaccinators while the EU worked through its red tape.
Now the 27 countries of the EU have the example under their noses which they dreaded. That post-Brexit UK is more nimble than they are. The UK's vaccine facilities are producing gobs of vaccine. The ones on the continent are experiencing "teething problems".
They are in a jealous rage. But it's a bit like with the Trump Republicans who can't admit reality. The EU has some strengths. But it is slow moving and institutionally arrogant. And this is why it doesn't always have virtue and efficiency on its side. Its poor performance in getting its covid19 response going is a case in point.
On another note, the pols, journallists and twitterati who chided the British for its Brexit are hiding out right now. We know why.