Does any country track what % of its vaccinated had previously had the virus? Can they even definitively say if someone hasn't? Unless they have this number its impossible for them to even estimate how much the vaccine prevents hospitalizations or deaths. I know that you can't even to begin tracking this in the USA for political reasons, but does anyone else try?

Unrelated question, what's the deal with the chink vaccine that just contains the virus itself? Does that one supposedly do anything? Do the make fantastical claims about it not preventing infection but somehow being relevant?