News has come out that about 10% of the population may have "pre-existing immunity" to symptoms.
This was a conclusion of doctors at UC San Francisco.
This is probably why so many people have become anti-vaxxers? My brother and sister, who share a small house, both got covid in June. She had had "a really bad cold" in January but declined to be tested. He is 60 and had two vaccines while she only had one. Neither was boosted. She had a heart attack in June, tested positive for covid on admission, and soon died from a second heart attack (leftover clots from January?). He was en route to my house when all this transpired, and we did a covid test after learning she had it. He tested positive but had zero symptoms. I'm thinking he has the HLA gene.