“The most common side effects to COVID vaccines include pain at the injection site, fevers, chills, nausea, headaches, tiredness, and painful or swollen lymph nodes in the arm where the vaccine was injected,” says Dr. Vivek Cherian, M.D., a Baltimore-based internal medicine physician.

“Because the body has already started to develop antibodies (it has already been primed) after your first dose, your body responds more robustly after your second dose and you are more likely to be fatigued or have more pronounced side effects in general,” says Dr. Vivek Cherian, M.D., a Baltimore-based internal medicine physician.