There was an interesting study re-published on CNN that said the more side effects you suffer after the vaccines the more susceptible to severe Covid you are likely to be. I.e, the most aggressive forms of Covid are normally due to an 'over active' immune response which causes those people to react more to the vaccines. I had the 2 shot Pfizer, had a sore arm after both doses and that was it. My wife was floored for 3 days after the second shot.