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If You Feel This, Your COVID Vaccine Is Working

These reactions are normal and mean the vaccine is doing its job, say experts.
FACT CHECKED BY Emilia Paluszek

Certain side effects are to be expected after your COVID vaccine. The CDC says these "are normal signs that your body is building protection. These side effects may affect your ability to do daily activities, but they should go away in a few days. Some people," they note, "have no side effects." So which side effects are the "good" ones and which are ones you should worry about? Read on—and to ensure your health and the health of others, don't miss these Signs Your Illness is Actually Coronavirus in Disguise.


You Might Feel a Pain, Redness or Swelling on the Arm Where You Got the Shot

Senior woman with arm pain

Dr. Anthony Fauci, the chief medical advisor to the President and the director of the National Institute of Allergy and Infectious Diseases, said he felt a little pain in his arm. "Getting that reaction at the site is exactly what we would expect a vaccine to do that is trying to mimic a pathogen without causing the disease," Deborah Fuller, a vaccinologist at the University of Washington School of Medicine, in Seattle, tells National Geographic.


You Might Have a Fever or Chills

Ill woman lying in bed looking at thermometer suffering from seasonal flu and infectious disease

A fever, chills and the other side effects on this list are a good sign, say doctors. "And we know why this happens—because the vaccine is very potent in inducing an immune response. That's one of the reasons why we're getting such high levels of protection" against COVID-19, Dr. Peter Hotez, a vaccinologist and dean of the National School of Tropical Medicine at Baylor College of Medicine, told CNN.


You Might Feel Aches or Muscle Pain

Woman is touching her stiff shoulder.

"The vaccine, because you're giving it in the arm, it gives a systemic reaction. You know that because sometimes after the second dose you feel a little achy, a little chilly, which means the immune system is really getting revved up," said Dr. Fauci in an interview with MSNBC.


You Might Be Tired or Fatigued

Woman sleeping on the couch in the living room.

Fauci said he felt a bit tired after his vaccine. "About 65% of vaccine recipients in Pfizer's and Moderna's trials, and 38% in Johnson & Johnson's, developed fatigue," says Business Insider.


You May Get a Headache

Sick woman suffering from head ache

"If you're experiencing common side effects such as a headache, fever or chills after receiving the COVID-19 vaccine, it's perfectly fine to take an over-the-counter pain reliever such as ibuprofen or acetaminophen to relieve your discomfort, experts say," according to AARP.


You May Get Nausea

Sick woman coughing, experiencing hiccup.

Says the Cleveland Clinic: "The data shows that side effects are more commonly felt after the second dose of Pfizer or Moderna's vaccine rather than after the first dose. With Johnson & Johnson, the most commonly reported side effects were arm soreness, headache, muscle aches and nausea. Most of the side effects occurred one to two days after vaccination."

RELATED: Most COVID Patients Did This Before Getting Sick


You May Feel Nothing at All!

Happy woman sitting on a couch

Not everyone experiences side effects, and that does not mean your vaccine isn't working. "The big take-home message is that not having side effects, or [having] not as severe side effects, is no reason to worry," John Wherry, an immunologist at the University of Pennsylvania, told Scientific American.


When to Worry About Any Side Effects

Health visitor and a senior man during home visit

"In most cases, discomfort from pain or fever is a normal sign that your body is building protection," says the CDC. "Contact your doctor or healthcare provider:

  • If the redness or tenderness where you got the shot gets worse after 24 hours
  • If your side effects are worrying you or do not seem to be going away after a few days

If you get a COVID-19 vaccine and you think you might be having a severe allergic reaction after leaving the vaccination site, seek immediate medical care by calling 911." And to protect your life and the lives of others, don't visit any of these 35 Places You're Most Likely to Catch COVID.

Alek Korab
Alek Korab is a Co-Founder and Managing Editor of the ETNT Health channel on Eat This, Not That! Read more about Alek