What are side effects of the COVID-19 vaccine?

“Well you’ve already received some of the first vaccine, of course, which causes your body to be ready if it’s exposed again. So in that state of readiness, when that second exposure comes and your body begins to produce those proteins associated with the virus your immune system jumps on it and it starts firing on all cylinders,” Dr. Springgate said. “Part of the usual way your body does that is by activating the immune system, activating inflammation and doing all it can to make sure you don’t become infected or your infection is minimized.”