See also the forthcoming deadline (June 23rd) for opting out from having all your data irretrievably slurped by the likes of palantir: https://medconfidential.org/how-to-opt-out/
Plus 'nudge' tactics are out to play in full force - I particularly dislike the pre-emptive strike at social media implying information there would be false despite there not actually being anything on there at the time (I say this as someone who loathes Facebook et al with a passion).
I guess there's a lot of money at stake (there's gold in them thar personal medical records).
Edit: looks like it's England only, but I'm going to make a wild guess and say they didn't get a letter either. Which should have been an opt in thing, by the way!
I personally believe it’s a question of when, not if, the country-wide database is hacked or leaked.