Man in 2020 were sh*tting bricks, as lungs and heart have classically been rather non-athletic (was in pretty good shape in mil, but never took to track & field / ball sports as a young lad, other than running to train for boot camp). Even took to running with mask during pandemic, to get used to wearing them under duress (which helped in hindsight w/ working hard client problems on the table). Religiously washed hands, gapped 2m, avoided mixed gatherings, all the sane things a healthcare provider would do. Point being, no symptoms post-vax, indeed doesn't mean the vax hasn't taken and provided protection... though didn't take any chances. Haven't tested positive nor covid symptom'd since Jan 2020, when came down with the worst congestive flu-like symptoms I'd ever had to that point, save one that nearly killed me 30y prior (fever of 106.7F / 41.5C; ice bath dunk and everything; no memory past being groggy in the sick call cattle cart). After that all sorts of tests -- from the old slow clinic ones requiring serum processing, to home self-tests -- all negative.