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Why do some people get side effects from the COVID vaccine?

Health care workers answer questions about the COVID-19 vaccines.

Shaquita Bell, MD explains what that achiness some people feel after the COVID vaccine means, and why it’s a good thing!

So that’s a great question. People ask me, “Why do I get side effects?” And you probably have seen that almost any vaccine and sometimes many medications will give you side effects. So a lot of times, I sort of compare it to like your body is still learning. What is it supposed to fight and what does, it’s not supposed to fight? So your body’s getting ready to learn all those exercises on how it’s going to keep you safe from coronavirus. So your immune system really activates when you get the vaccine, it says, “Hey, we’re ready. Let’s fight it. Let’s learn. Let’s learn these exercises to prevent coronavirus infection.”

And that can cause you to feel a little bit, you know, kind of crummy, like your body, you personally are like, “What’s going on? Why does my neck hurt? Why does my head hurt?” And that’s really just your body doing its thing. And it’s very natural. It’s a very natural process of your immune system ramping up. And it is very, also very short. So it’ll go away. It’s temporary. You won’t always have pain at the site. You won’t always have a headache. You won’t always have muscle aches that that’s just temporary while your immune system is learning. And then it’ll be ready when you put it into action.

This information is shared for educational purposes only and should not be used as a substitute for professional medical advice. The views expressed are those of the featured medical professional and reflect information available to that professional at time of filming. Always consult a health care provider for any personal health decisions. Click here for vaccine FAQs from the CDC.

Stay up to date with your COVID vaccine, including boosters!

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Immunity wanes over time. Keep up your protection against COVID by getting boosted when eligible.

Updated boosters are available for adults and children 6 months and older.