First shot- nothing.
Second shot- chills started about 7 hours later. Next day, super tired, sore throat and headache. I let him skip school but he did go to band practice (because it was his very first one and didn't want to miss it). Stayed home the next day but did school virtually because he was still tired and had a sore throat. He seems to be all better now so just 2 days of not great following shot 2.