It hasn't "proven" to do any such thing yet. Trials and mass real world time experience are not the same. We'll have to wait on that until next autumn and winter when the hammer will be right down again on this seasonal virus.
We have new variants that could cut right through the efficacy of these current vaccines also.
The vaccines are not the answer, they are an aid. Behavioural changes adopted for the long term like social distancing and face masks, and the reorganisation of the economy (and especially the hospitality sector are the main ways we suppress the virus, not the vaccines).
Government ministers talking about hosting the Euros is criminal.
I can't be arsed with your first points. Not going over the same ground.
On the bold part, in terms of just hosting the tournament, it makes total sense and is the only feasible solution to get the tournament on.
All 24 teams would have their own bubble at the training grounds (the majority of which have their own sleeping facilities, btw).
The groups would be based at grounds near to the training grounds, so limited travel for the teams.
They'd all have to come here at least a week before the tournament anyway, so probably just tweak that to 10 days to include for some days of isolation.
Putting fans aside for one minute, it is absolutely fine for the UK to host the tournament this year in terms of just having a place to play the games. And it's the only solution that makes sense.
If fans can go, then you just have very limited capacity in these massive stadiums, restrict the ballots to the city areas (like the Everton and Liverpool games before Xmas), and everyone who goes has to have that negative covid test 24 hours before, and probably masks will have to be a thing even when sat down.
Middle of summer and the entire adult population will hopefully have had their first jab by the time the tournament starts.
