A few months ago I volunteered to do a COVID19 study. I answer a daily health survey and take a C19 blood test every month for six months.
As expected, my first three blood tests were clear - no sign of current or previous infection. My fourth test was a week after my first shot of the Pfizer vaccine, and it also came back clear. My fifth test I did today, two weeks after my second shot and ... it says I have long-term C19 antibodies! Hooray!