Thank you. I got sick and know it was different, and did leave me feeling poorly for several months. The first early fear about covid vaccines was that they would lead to an enhanced hyper immune reaction as the attempts at SARS-1 vaccines did ("all the animals died"). Well, it turned out worse for various reasons, but if one corona virus can have this antibody enhancement effect on reexposure after infection or vaccination, maybe others can too and increasing age means increasing chance of previous exposure, as Corona virus are common.