@wjt FWIW, you can have a seasonal covid19 booster shot in the UK if you tick the box that says you care for someone who is vulnerable. I couldn't find a strict definition of what caring for someone should involve, was maybe a little bit of a reach in my case (I visit my parents regularly), but there were no further questions and I think at this stage in the vaccination drive, you're not depriving anyone else by taking a shot.