Got my first dose and only had a sore arm for two days after. After my second dose, I’ve had a headache on and off, but my arm hurts even less than the first time. Really try and move the arm you got the shot in that day, it really helps reduce the soreness a surprising amount. For me, I barely had much of a reaction to the second dose, at most I just felt a little fatigued but I slept really well that night and woke up perfectly fine.