I don’t think it’s reasonable to hand over our vaccines for “the vulnerable” in other countries, only for those countries to vaccinate celebs, MPs, athletes, the wealthy, etc.
The vaccines would have to get there first 
I know it won't happen, but let's suppose that all the "unselfish" gave up theirs so (insert country of choice) could have them ... given we can't exactly bung 'em in an envelope, who'd be in charge of this?
The pharma companies? Doubt they'd be keen to alter existing contracts and take a punt on getting paid elsewhere
Covax / the WHO themselves / the EU? Good luck with that, given current performance
Someone else I've not thought of?
Come to think of it, maybe those envelopes aren't such a bad idea after all ...