I had Moderna vaccine. No reaction to first shot. Second shot: had a series of ‘symptoms’ over three days as my immune system tossed one response after another at the introduction of the vaccine into my system. I felt ‘bad’ for several days but as my immune system worked through the challenge, I never felt ‘sick’, as in ‘really sick’, because I knew my immune system was deliberately ‘giving me a fever’, then ‘cleaning out my digestive system’ etc etc...each of these lasting about 4-6 hours before moving on and trying something else. Once it went through it’s complete repertoire of responses it just...stopped ...and I felt fine again. Strange experience to be sure but I would do it again given the peace of mind I got as a result.