bit confused about all this
Firstly, we don't seem to know a lot of the details, such as how much of the UK's vaccine supply is coming from the EU. I imagine regardless of contracts, there is not much the UK could do about that if the EU blocks shipments, anymore than the EU can do much to for the UK to deliver vaccines from its plants to the EU.
Secondly, the WHO has condemned the EU for threatening to block exports, because it is "morally wrong" to embark on vaccine nationalism. Yet if the UK has contracts that require AZ to deliver to them first, even if it means shipping EU produced vaccine to them to complete vaccinating everyone (100m doses) before many of the most vulnerable old people in the EU have been vaccinated, that doesn't seem any different in terms of preventing others having the vaccine until you have satisfied all your own needs. Legally you might be relying on contracts rather than emergency export bans or whatever, but we're talking morally not legally. It seems exactly the same to me. Has the WHO condemned the UK?
Thirdly, it seems reasonable legally that any block like the UK, US or EU can force through heavy handed export bans in cases of national security. Now I suppose you could argue that vaccinating your population is a dubious use of 'national security', but then again, the UK has specifically refused to allow its contract with AZ to be published due to 'national security'. It would therefore be rather difficult to argue both angles at the same time.
I suspect that this will all be moot in a month or two. The EU production will ramp up, and by early summer everywhere will be swimming in vaccines, probably while the last virus wave was taken down by lockdowns anyway.
But it may well have poisoned relations, which is pretty bad news as I work in ecommerce and basically none of my clients are able to ship stuff to the EU due to paperwork, and orders have collapsed. At present, the UK is not applying checks to incoming shipments from the EU, but they plan to implement that soon. At that point, there will be total collapse in trade. And I guess banks hoping to get equivalency are screwed now, it seems there is very little goodwill left.
Whatever happens, there needs to be talks over smoothing out trade, because long term the present arrangement is going to kill many businesses.