I had a massive reaction to my first covid jab (Pfizer: fever and chills, followed by a multi week flare and brain fog), a moderate reaction to the second (Pfizer: some aching, followed by multi week brain fog). And very little reaction to the Moderna bivalent, at least that I noticed. I was grateful, because the whole multi week brain fog thing is Not Fun. But at least you know your system is better protected now?