Anecdotally: I know a number of people who say they "had COVID" but when you poke a little bit deeper it turns out they never had a formal diagnosis or test res

Anecdotally: I know a number of people who say they "had COVID" but when you poke a little bit deeper it turns out they never had a formal diagnosis or test result -- they just self-diagnosed based on some symptoms. I have no data about the numbers here, but I suspect that these people make up a non-trivial percentage of the "already had COVID" crowd. Vaccination seems like a pretty good precaution for these folks.