https://www.bbc.com/news/health-59207466
So basically, natural immunity WITHOUT having to actually get Covid.A team at University College London said some people had a degree of Covid-immunity before the pandemic started. This likely came from the body learning how to fight viruses that are related to the one which has swept the world. Upgrading vaccines to copy this protection, could make the jabs even more effective, the team said.
The scientists were closely monitoring hospital staff during the first wave of the pandemic - including by taking regular blood samples.
Despite being in a high-risk environment, not everyone in the study came down with Covid. The results, published in the journal Nature, showed some people just managed to avoid the virus.
...
Blood samples showed these people already had (as in before the pandemic) protective T-cells, which recognise and kill cells infected with Covid. Dr Leo Swadling, one of the researchers, said their immune systems were already "poised" to fight the new disease. These T-cells were able to spot a different part of the virus than the bit most of the current vaccines train the immune system to find.
ALSO - found this article from 2011 titled "Swine flu offers 'extraordinary super immunity'" - right after my time working at the school, I caught the secondary wave of H1N1 flu that was around in 2015. I got so sick from that there was one day I wondered if I was going to die. I couldn't even sit up in bed. That was 2015. Interestingly enough, I haven't had a single cold or flu (or Covid) since then.
https://www.bbc.com/news/health-12152500