Obviously this thread shows it's possible. but according to the limited data I can see on it, it seems it's incredibly rare, other than the most at risk groups who should probably get another booster.
I've said for a while, and still firmly believe it. Natural immunity will be a big part of the real winner here. If vaccinations can help reduce deaths for many who then become naturally immune later, even better. But I bet once we have 60-70% of the population having had this thing at least once, and can fight if off better the 2nd time, along with 60-70% vaccinations, that's when the waves get down to next to nothing. I bet we are around 40-45% of people having had it. With Delta, it might be even higher now in areas like Texas or Florida. Maybe 40-50% natural immunity and 70-75% vaccinations would do it, too. I don't know. Somehow you need to combing to having about 80+% of the population immune from going to the hospital to prevent this, IMHO.
On the other hand, I guess hundreds of people read a thread like this, so finding 3-4 examples of it happening shouldn't be too shocking. But I always find it amazing how many statistical outliers you read about on this board, or when you go to twitter, that I never hear about in real life, or find real world data that it's common at all. And I/we have most definitely not tried to avoid covid in my friends or family. I know of maybe 15 people, if you include work so not even friends, who have verified that they have tested positive for it. No one was worse than the flu. Not a single 2nd case. Only one minor case post vaccination. Not a single hospitalization in people I actually know (I know of 3 friends of a friend of a friend, that I never actually met who died. But that's it)