Key Takeaways

PotentialCOVID-19 vaccine side effectshave been a big concern for people who are nervous to get the shot. However, new research has found that many of the side effects people report are actually just a placebo effect.

How Placebos Work

Systemic vs. Local Side EffectsSystemic side effects are felt in the whole body (e.g., muscle aches) rather than in just one spot (e.g., pain in the arm where the shot was given).

Systemic vs. Local Side Effects

Systemic side effects are felt in the whole body (e.g., muscle aches) rather than in just one spot (e.g., pain in the arm where the shot was given).

The researchers found that 35% of the people who got the placebo shot reported having systemic side effects after getting their first dose. After getting the second dose of the vaccine, 32% of the placebo group reported systemic side effects.

The most common symptoms were headache (19.6%) and fatigue (16.7%).

Expect Mild Side Effects From COVID-19 Vaccines

However, the people who got therealCOVID vaccine reported more side effects than the people who got the placebo shot. The researchers found that after getting their first dose of the real vaccine:

After getting their second dose of the vaccine:

The Placebo Effect

However, some of these side effects also happened in the placebo group. Since these people did not get the real COVID vaccine, that means that their side effects didn’t happen because of the shot. If a person has side effects from a placebo treatment, it’s called the placebo effect.

Therefore, the researchers estimated that the placebo effect was responsible for 76% of the side effects that the people in the placebo group reported after getting their first dose and 52% of the side effects they reported after getting their second dose.

Are COVID Vaccine Side Effects Contagious?

The researchers used the term “nocebo” to describe what the people who received a placebo experienced. The “nocebo effect” is when a person’s expectations about experiencing something negative after a treatment (e.g., a vaccine side effect) make them more likely to have that negative experience.

The researchers concluded that their study “found that the rate of nocebo responses in placebo arms of COVID-19 vaccine trials was substantial.”

COVID Vaccine Side EffectsThe potentialside effects of a COVID-19 vaccinecan vary from person to person. Some people don’t have any side effects at all.In general, the most common local vaccine side effects include:PainRednessSwellingThe most common systemic vaccine side effects include:TirednessHeadacheMuscle painChillsFeverNausea

COVID Vaccine Side Effects

The potentialside effects of a COVID-19 vaccinecan vary from person to person. Some people don’t have any side effects at all.In general, the most common local vaccine side effects include:PainRednessSwellingThe most common systemic vaccine side effects include:TirednessHeadacheMuscle painChillsFeverNausea

The potentialside effects of a COVID-19 vaccinecan vary from person to person. Some people don’t have any side effects at all.

In general, the most common local vaccine side effects include:

The most common systemic vaccine side effects include:

A Timeline of COVID-19 Vaccine Side Effects

The ‘Nocebo Effect’ Is Common

Thomas Russo, MD, a professor and the chief of infectious disease at the University at Buffalo, told Verywell that the nocebo effect is common. That’s why it’s so important that when researchers are testing the efficacy of treatments like vaccines, they “run a control or placebo group.”

Amesh A. Adalja, MDThe placebo effect is a strong and real phenomenon.

Amesh A. Adalja, MD

The placebo effect is a strong and real phenomenon.

Russo added that the nocebo effect doesn’t just happen with COVID shots. “In any trial, there are side effects in the placebo group,” and “it’s how people react when they perceive that they receive something versus the true cause and effect of that something.”

Why the Nocebo Effect Happens

Doctors say that there are a few potential reasons why the nocebo effect happens.Richard Watkins, MD, an infectious disease physician and a professor of internal medicine at the Northeast Ohio Medical University, told Verywell that one is simply due to the expectations people have.

Richard Watkins, MDThis shows how the vaccines are much safer than many people perceive them to be.

Richard Watkins, MD

This shows how the vaccines are much safer than many people perceive them to be.

“People have been conditioned that, if they receive a shot, they are going to have some kind of adverse reaction,” said Russo, adding that other people are just nervous about needles and may have a reaction based on that fear.

“Some people have a perception that their body has been invaded,” said Russo. “As a result, they may develop symptoms that are independent of the vaccine.”

Fear of COVID-19 Outweighs Fear of Vaccine Side Effects

Experts stress that the study’s findings indicate that side effects from the COVID vaccine itself are not as common as many people think.

“This shows how the vaccines are much safer than many people perceive them to be,” said Watkins. “If you subtract out the perception of injection-related side effects versus side effects due to the vaccine itself, the actual number of side effects are much less,” Russo said.

Adalja urged people who are nervous about getting a COVID vaccine to consider that “overall, the COVID-19 vaccines are very safe and a lot of reactions people may experience may be unrelated to the vaccine’s contents.”

What This Means For YouLike with any vaccine, the COVID-19 vaccines can have side effects. However, recent research shows these side effects may not be as common as people may think.If you’re nervous about getting vaccinated because you’re worried about having side effects, share your concerns with your doctor. They can make sure you understand how the vaccines work, why they’re safe, and the risks and benefits of getting vaccinated.

What This Means For You

Like with any vaccine, the COVID-19 vaccines can have side effects. However, recent research shows these side effects may not be as common as people may think.If you’re nervous about getting vaccinated because you’re worried about having side effects, share your concerns with your doctor. They can make sure you understand how the vaccines work, why they’re safe, and the risks and benefits of getting vaccinated.

Like with any vaccine, the COVID-19 vaccines can have side effects. However, recent research shows these side effects may not be as common as people may think.

If you’re nervous about getting vaccinated because you’re worried about having side effects, share your concerns with your doctor. They can make sure you understand how the vaccines work, why they’re safe, and the risks and benefits of getting vaccinated.

What Are COVID Booster Shot Side Effects Like?

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit ourcoronavirus news page.

3 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Haas JW, Bender FL, Ballou S, et al.Frequency of adverse events in the placebo arms of COVID-19 vaccine trials: a systematic review and meta-analysis.JAMA Netw Open.2022;5(1):e2143955. doi:10.1001/jamanetworkopen.2021.43955Planès S, Villier C, Mallaret M.The nocebo effect of drugs.Pharmacol Res Perspect. 2016;4(2):e00208. doi:10.1002/prp2.208Centers for Disease Control and Prevention.Possible side effects after getting a COVID-19 vaccine.

3 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Haas JW, Bender FL, Ballou S, et al.Frequency of adverse events in the placebo arms of COVID-19 vaccine trials: a systematic review and meta-analysis.JAMA Netw Open.2022;5(1):e2143955. doi:10.1001/jamanetworkopen.2021.43955Planès S, Villier C, Mallaret M.The nocebo effect of drugs.Pharmacol Res Perspect. 2016;4(2):e00208. doi:10.1002/prp2.208Centers for Disease Control and Prevention.Possible side effects after getting a COVID-19 vaccine.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

Haas JW, Bender FL, Ballou S, et al.Frequency of adverse events in the placebo arms of COVID-19 vaccine trials: a systematic review and meta-analysis.JAMA Netw Open.2022;5(1):e2143955. doi:10.1001/jamanetworkopen.2021.43955Planès S, Villier C, Mallaret M.The nocebo effect of drugs.Pharmacol Res Perspect. 2016;4(2):e00208. doi:10.1002/prp2.208Centers for Disease Control and Prevention.Possible side effects after getting a COVID-19 vaccine.

Haas JW, Bender FL, Ballou S, et al.Frequency of adverse events in the placebo arms of COVID-19 vaccine trials: a systematic review and meta-analysis.JAMA Netw Open.2022;5(1):e2143955. doi:10.1001/jamanetworkopen.2021.43955

Planès S, Villier C, Mallaret M.The nocebo effect of drugs.Pharmacol Res Perspect. 2016;4(2):e00208. doi:10.1002/prp2.208

Centers for Disease Control and Prevention.Possible side effects after getting a COVID-19 vaccine.

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