".. it is quite likely that we would never have found out whether a population pre-immunity existed or not. If it wasn’t for Sweden which, to everyones surprise, decided to combat the pandemic with relaxed NPI’s.."

https://www.medrxiv.org/content/10.1101/2021.07.07.21260167v1.full

https://www.fumento.com/articles/the-swedish-alternative-coping-with-a-virus-while-preserving-livelihoods-and-liberties/