- Many vaccines have side effects. Most are mild, indicating that your body’s immune system is learning to respond.
- Minor side effects from the COVID-19 vaccine are common and not serious. A small number of people may experience more serious side effects, including allergic reactions. If you have a history of severe allergic reactions, talk with your provider before getting vaccinated.
- The absence of side effects does not mean the vaccine is ineffective. If you experience mild side effects after the first dose, don’t let that stop you from taking the second. You need to take both doses within the recommended time frame to be protected.
Members of the Advisory Committee on Immunization Practices (ACIP), which advise the Centers for Disease Control and Prevention (CDC), meet regularly to discuss COVID-19 vaccines.
The organization encourages healthcare providers to be honest with their patients about vaccines, especially possible side effects.
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Many people are not sure what to expect after getting the COVID-19 vaccine. Health experts, including ACIP members, worry that people may not get vaccinated if they worry about side effects.
At a meeting in November 2020, committee members stated that “early experience [the] Vaccines will be very important to increase interest and demand. Transparency is critical to increasing trust and acceptability. “
Transparency for healthcare professionals involves educating patients about vaccine expectations. This includes minor side effects such as:
- pain or swelling at the injection site
The Centers for Disease Control and Prevention (CDC) advises that people may experience some discomfort for a few days after getting the vaccine. They may feel a bit like they have the flu, with mild fever and fatigue.
Some people experienced side effects after the second dose of the vaccine, but not the first. If you do have mild side effects after taking the first dose, don’t let that stop you from taking the second dose. You need to get both doses within the recommended time frame to be protected.
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At a press briefing hosted by the Infectious Diseases Society of America, Kathleen M. Neuzil, MD, MPH, FIDSA, director of the Center for Vaccine Development and Global Health at the University of Maryland School of Medicine, explained that these side effects “are all signs that a vaccine is developing. The immune response, as we hoped.”
While mild side effects indicate that the vaccine is working, the absence of side effects does not mean the vaccine is not working. Also, having certain risk factors that increase your chances of getting COVID-19, such as being older, doesn’t necessarily mean you’re more likely to have vaccine side effects.
If you have questions about what to expect after getting the COVID-19 vaccine, or if you are concerned that your experience is not normal, talk to your doctor. The CDC website is another source of reliable and up-to-date information about the COVID-19 vaccine, including known possible side effects.
Side effects in clinical trials
The companies that make the three currently available COVID-19 vaccines — Pfizer, Moderna, and Johnson & Johnson — have released data on the side effects people experience during vaccine clinical trials (ensuring that the vaccines work and that they are safe).
Of the three COVID-19 vaccines, Pfizer is the first to receive full approval from the U.S. Food and Drug Administration (FDA). Moderna’s vaccine is the second fully approved vaccine.
COVID-19 vaccine: Moderna and Pfizer
Pfizer vaccine side effects
Overall, the vaccine was well tolerated by most of the more than 43,000 participants in Pfizer’s vaccine trial. The most frequently reported serious (grade 3) side effects were fatigue (3.8% after first or second dose) and headache (2% after second dose).
Other side effects that people could report as serious occurred in less than 2% of the trials and were therefore considered insignificant.
In another clinical trial of 3,100 people 5 to 11 years old who received the vaccine, the most common side effects were injection site pain, redness and swelling, fatigue, headache, muscle and/or joint pain, chills, fever, Swollen lymph nodes, nausea, and decreased appetite. Overall, they are considered mild to moderate and usually go away within a day or two.
The U.S. Food and Drug Administration (FDA) notes that side effects can last for several days and appear to be more common after a second dose of the vaccine. Common side effects include injection site pain, tiredness, headache, muscle pain, chills, joint pain and fever.
Moderna vaccine side effects
Most of the side effects reported by more than 30,000 participants in Moderna’s vaccine clinical trials were mild and did not last long. Like Pfizer, Moderna noted which side effects were rated serious and reported at a frequency of 2% or higher. There were some differences in reported side effects between the first and second doses.
The most frequently reported serious side effect after the first dose was injection site pain (2.7%). Other side effects were reported after the second dose, most of which were mild and disappeared quickly.
The most commonly reported side effects rated serious after the second dose of the vaccine were:
- 9.7% Fatigue
- 8.9% Muscle soreness
- 5.2% joint stiffness
- 4.5% headache
- 4.1% Pain
- 2% erythema/redness at injection site
As with Pfizer’s vaccine, the FDA noted that people experienced side effects after receiving either dose, but reported more frequently after a second dose.
Johnson & Johnson vaccine side effects
Preliminary vaccine safety information released shows that the most common reactions following vaccination include:
- pain, redness, or swelling at the injection site
- Muscle pain
Ask an infectious disease expert: What can we expect from a COVID-19 vaccine?
rare and serious side effects
Although uncommon, some people have experienced more severe or unusual side effects after receiving the COVID-19 vaccine. Some of these side effects, such as fainting (syncope), are related to the injection (vasovagal reaction). These side effects can be distressing, but are usually not serious. However, they need to be prevented because people can get hurt when they faint.
Other reactions are caused by allergies and can be serious. According to the CDC, a small number of people have developed allergic reactions after being vaccinated against COVID-19. Severe reactions usually occur shortly after a person is vaccinated, usually within a few minutes.
Both Pfizer and Moderna recommend that people seek immediate medical attention if they develop certain symptoms within hours of getting the COVID-19 vaccine. These symptoms include difficulty breathing, a rash, and swelling of the face or throat.
CDC: Severe allergic reactions to Pfizer’s COVID vaccine rare
All providers of the COVID-19 vaccine must know what to do if someone has a severe reaction after being vaccinated. This may include knowing how to use the EpiPen or seeking emergency care.
The CDC recommends that people with a history of severe allergies, including anaphylaxis, speak with their provider before getting the COVID-19 vaccine.
The CDC says that if a person has had a severe allergic reaction to any of the ingredients in either vaccine, they should not be vaccinated. If someone has a severe reaction to the first dose of the vaccine, the second dose should not be given.
Updated the Pfizer and Moderna COVID-19 Vaccine Fact Sheets for healthcare providers, vaccine recipients and caregivers to address the rare risks of myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the outer wall of the heart).
Johnson & Johnson’s fact sheet also added a warning about the rare risk of thrombocytopenia and Guillain-Barre syndrome thrombosis for health care providers, vaccinators and caregivers.
The CDC continues to recommend a COVID-19 vaccine because the potential benefits clearly outweigh the known and potential risks.
Talk to your provider
C. Buddy Creech, MD, MPH, FPIDS, director of the Vanderbilt Vaccine Research Program, explained in a news release that the side effects seen so far in COVID-19 vaccine clinical trials are similar to those common to other vaccines.
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“We’re very reassured that we’re not seeing the unexpected,” said Creech, principal investigator of the clinical trial of Moderna and Johnson & Johnson’s vaccine. Not everyone who gets the vaccine will experience side effects, Creech added.
“It’s very important that people understand what they should expect,” Leana Wen, MD, MS, emergency physician and visiting professor of health policy and management at George Washington University, told VigorTip. “Side effects from vaccines are very normal. It’s the body’s response to boosting the immune system. People will respond differently, or not respond at all, as with all vaccines”
Wen said that when she and her fellow physicians recommend patients get the COVID-19 vaccine, “we shouldn’t try to minimize side effects; we should explain it to them.”
what does this mean to you
You may have mild side effects when you get the COVID-19 vaccine, but this is to be expected and a normal part of your body’s response. If you have any concerns, please consult your healthcare provider. While more serious side effects can occur with vaccines, they are rare. If you are allergic to or have had an allergic reaction to another vaccine in the past, you should discuss the COVID-19 vaccine with your provider.
The information in this article is current as of the date listed, which means that you may have updated information as you read this article. For the latest updates on COVID-19, visit our Coronavirus news page.