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VERIFY: Your COVID-19 shots didn't cause side effects, does that mean they didn't work?

Doctors say injection site pain, fever, and headache are normal responses to the COVID-19 vaccines and show immunity is building. What if you don't feel anything?

CHARLOTTE, N.C. — Health officials have said mild to moderate side effects are expected and normal with the currently approved COVID-19 vaccines. In fact, doctors say it's a sign the immune system is responding to the shot.

So, what if you get vaccinated and don't feel anything?


If you don't have side effects from your COVID-19 shots, does that mean the vaccine did not work for you?


Not necessarily. Doctors say there was a "significant" percentage of participants in the Pfizer and Moderna vaccine trials who did not demonstrate the common side effects.

WCNC.com reader Carmen Christensen first posed this question after receiving her second vaccine shot and noting she did not feel anything particularly adverse in the days afterward.

"That was the 11th of February," said Christensen, of when she received that final dose. "(On the) 12th–nothing. 13th–nothing. 14th–nothing. So, I have had no side effects from either one of them."

According to the Centers for Disease Control and Prevention, pain in the injection arm, fever, chills, tiredness, and headache are all normal reactions to the vaccine and signs "your body is building protection."

RELATED: VERIFY: So, you've been vaccinated. Is it now safe to visit family?

Christensen wanted to know if the lack of side effects was a sign that her shots weren't working.

Dr. Meg Sullivan, Medical Director for Mecklenburg Public Health, said not necessarily.

"The lack of side effects does not indicate that the vaccine is not working," said Sullivan.

Similarly, a lack of harsher second-dose side effects, which the CDC also states are more common, doesn't necessarily mean the shots are not working.

RELATED: VERIFY: Does the second COVID-19 shot cause stronger side effects?

"It's not a guarantee," Dr. Brannon Traxler, Interim Public Health Director for South Carolina's Department of Health and Environmental Control, said. "Not everybody who gets their second dose feels this way."

Food and Drug Administration briefing documents for Pfizer and Moderna vaccines show the top three reactions for both products were injection site pain, fatigue and headache.

Below are the shares of both trials' participants who reported these symptoms.

Credit: WCNC

While some of the reactions were quite common, Sullivan said the data still shows "there was a significant percentage of people that did not have side effects."

Side effects or not, it's important to note that anyone fully vaccinated still needs to follow COVID-safe protocols like masking and social distancing, according to CDC guidance.

While Christensen has a little more peace of mind knowing her lack of side effects doesn't necessarily mean her shots didn't work, she still plans to take care.

"I'll still wear the mask after my two weeks. I'm still going to be safe until all of this is over," Christensen said.

Have a relative or friend in another state and want to know when they can get vaccinated? Visit NBC News' Plan Your Vaccine site to find out about each state's vaccine rollout plan.

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