Don't freak out if you get these side effects from a Covid-19 vaccine -- they can actually be a good sign By: CNN By Holly Yan, CNN (CNN) -- With millions more Americans getting vaccinated every day, some have complained about fever, fatigue and other ailments they weren't expecting. Don't panic, doctors say. Side effects from Covid-19 vaccines won't last long. And they're actually proof that your immune system is working the way it's supposed to. (Though vaccines are still very effective even without side effects.) Here are some of the most common side effects from Covid-19 vaccines, how you can manage them, and why you shouldn't use them as an excuse to skip vaccination: