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What are common COVID-19 vaccine side effects?

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Millions of Americans have safely received a COVID-19 vaccine with only minor side effects.

The Centers for Disease Control and Prevention (CDC) reports that since December 2020, over 200 million doses of COVID-19 vaccine have been administered in the United States. That leaves about 140 million American adults — more than half — who still haven’t received even a single dose of a COVID-19 vaccine. Many have delayed getting the shot due to safety concerns over its short- and long-term effects.

Is there anything to worry about?

All the scientific studies published to date point to the same conclusion: The shots are safe. Like any vaccine, COVID-19 vaccines can cause side effects, but most are mild or moderate and go away within a few days on their own. Serious reactions are rare.

Most reported side effects are minor

Clay Dunagan, MD, BJC HealthCare chief clinical officer and infectious disease specialist, says the vaccines can cause side effects that are common to many vaccines, most lasting a day or two.

According to Dr. Dunagan, “Most commonly seen are the usual immediate effects or reactions from a vaccination, such as soreness at the injection site or feeling a little ‘under the weather.’

“Other reported side effects include fever, headaches, fatigue, and muscle and body aches in the days immediately following vaccination. Some have felt ill enough to stay home for a day or two.”

The COVID-19 vaccine is designed to prepare the body to fight coronavirus in the future. The commonly reported side effects are generally the result of a normal, healthy immune system responding to the vaccine.

The FDA noted that side effects after your second shot may be more intense than the ones you experienced after your first shot. Again, these side effects are normal signs that your body is building protection and should go away within a few days.

Not everyone experiences a reaction at all. In fact, most people do not. Those who don’t have side effects can expect to receive the same level of protection from the vaccine.

Common Side Effects of the COVID-19 Vaccine
Pain, redness, swelling on the arm where you got the shot    
Tiredness, fatigue
Muscle pain

The above reactions are common. A small number of people have had a severe allergic reaction (called “anaphylaxis”) after vaccination, but this is extremely rare. If this occurs, vaccination providers have medicines available to effectively and immediately treat the reaction.

After your COVID-19 vaccine, you will be asked to stay for 15–30 minutes so you can be observed and given treatment in the very rare event of a severe allergic reaction.

Despite the investigation of a possible link from the Johnson & Johnson/Janssen COVID-19 vaccine to a rare blood-clotting side effect, for most people the benefits of the vaccine far outweigh the risks of becoming infected with the COVID-19 virus. You can learn more about this in the frequently asked questions below.

Late Side Effects Are Unlikely

According to the CDC, serious side effects that would cause a long-term health problem are highly unlikely following COVID-19 vaccination. Late side effects following any vaccination are extremely rare. Vaccine monitoring has historically shown that if side effects are going to occur, they generally happen within six weeks of receiving a vaccine dose. For this reason, the Food and Drug Administration required each of the authorized COVID-19 vaccines to be studied for at least two months (eight weeks) after the final dose.

Millions of people have received COVID-19 vaccines, and virtually no late side effects have been detected to date. The CDC continues to closely monitor COVID-19 vaccines. If scientists find a connection between a safety issue and a vaccine, the FDA and the vaccine manufacturer will work toward an appropriate solution to address the specific safety concern (for example, a problem with a specific lot, a manufacturing issue, or the vaccine itself).

COVID-19 Vaccine Frequently Asked Questions

With a new vaccine, it’s normal for people to have specific questions about the safety and potential side effects — especially if you are living with a certain health condition. BJC HealthCare, along with our partners at Washington University School of Medicine, the CDC and the FDA are continuously learning and committed to sharing answers to your questions.

What Can I Do To Alleviate The Pain From Vaccine Side Effects?

If you experience any minor side effect, it should only last a couple of hours and no more than a few days. To reduce pain and discomfort at the injection site, apply a clean, cool, wet washcloth over the area, and use or exercise your arm. To reduce discomfort from fever, drink plenty of fluids and dress lightly. You can take Tylenol or Advil after you are vaccinated.

Do not take over-the-counter medicine before your vaccination for the purpose of trying to prevent side effects.

Should I get the vaccine if I have underlying health conditions?

People with suppressed immune systems, as a result of cancer treatment or autoimmune disease for example, can safely get the COVID-19 vaccine since it doesn’t contain a live virus. Again, you should talk to your doctor if you have concerns.

Can I Get COVID-19 From The Vaccine?

You cannot get COVID-19 from the vaccines. None of the vaccines contain any live virus or infectious matter. They are designed to cause your body to make copies of a small harmless piece of the coronavirus to develop an immune response, so you will not, and cannot, get COVID-19 from the vaccine.

Should I Get the Vaccine if I Have Allergies?

Regarding allergic reactions to the vaccines, the FDA notes that any vaccine or medication has the potential to cause severe allergic reaction. If you have had prior severe allergic reactions to other vaccines or if you have had reactions to the ingredients of the vaccines, the FDA currently recommends that you avoid these vaccines.

If you have allergies, especially severe ones that require you to carry an EpiPen, discuss the COVID-19 vaccine with your doctor, who can assess your risk and provide more information on if and how you can get vaccinated safely.

  • If you had a severe allergic reaction — also known as anaphylaxis — after getting the first shot of a two-dose COVID-19 vaccine, the CDC recommends that you not get a second shot of that vaccine.

  • The same holds true if you had an immediate allergic reaction after getting a shot of a COVID-19 vaccine. You should not get a second shot of that vaccine, even if your allergic reaction was not severe enough to require emergency care. An immediate allergic reaction happens within four hours of getting vaccinated and may include symptoms such as hives, swelling and wheezing (respiratory distress). Your doctor may refer you to a specialist in allergies and immunology to provide more care or advice.

When Should I Call My Doctor or Medical Specialist?

If you think you are having a severe allergic reaction, call 911 immediately. If it has been more than 48 hours after receiving your shot and you are experiencing persistent redness or tenderness at the site of the injection, rash, or persistent fever or chills, contact your doctor for advice. If you develop headaches, leg swelling or difficulty breathing in the two weeks after receiving the Johnson & Johnson/Janssen vaccine, contact your provider.

Should I Get the Vaccine if I Have Underlying Health Conditions?

Those with underlying conditions such as diabetes and heart disease are at high risk for experiencing complications from COVID-19. So, it is even more critical that they receive the vaccine. If you have concerns, consult with the doctor who is helping you manage the condition.

Should I Get the Vaccine if I Have a Suppresed Immune System?

People with suppressed immune systems, as a result of cancer treatment or autoimmune disease for example, can safely get the COVID-19 vaccine since it doesn’t contain a live virus. Again, you should talk to your doctor if you have concerns.

Should I Get the Vaccine if I’m Pregnant or Breastfeeding?

The CDC says it’s OK for pregnant women to get the vaccine, and advises they talk to their doctor if they are concerned about the risks and benefits of the vaccine. Pregnant women who contract coronavirus infection can have complications or pass the disease on to their babies, as can breastfeeding moms. Since the COVID-19 vaccine doesn’t contain a live virus, you can’t pass any infection on to the baby by being vaccinated.

What Should I Do if I Received the Johnson & Johnson/Janssen COVID-19 Vaccine?

Despite the investigation of a possible link from the Johnson & Johnson/Janssen COVID-19 vaccine to a rare blood-clotting side effect, for most people the benefits of the vaccine far outweigh the risks of becoming infected with the COVID-19 virus. 

More than 6.8 million doses of the Johnson & Johnson/Janssen vaccine have been administered in the United States and there have been a total of 15 reported cases (as of 4/27/21) of individuals developing blood clots within two weeks of receiving the vaccine. The clots were reported among women ages 18-48. Some cases have been serious, including one death. The FDA has reviewed all the data and recommended continued availability of the Johnson & Johnson/Janssen vaccine.  For women ages 18 – 50 who have easy access to an alternative vaccine, an alternative vaccine such as Pfizer or Moderna may be a little bit safer.  If Johnson & Johnson/Janssen is the only vaccine available, it is safer to be vaccinated with Johnson & Johnson than to be unvaccinated. BJC and Washington University will continue to follow the data and federal recommendations closely. If you received the Johnson & Johnson/Janssen vaccine more than two weeks ago without any problems at that time, there is no reason to be concerned now.

Anyone who has received the Johnson & Johnson/Janssen COVID-19 vaccine in the last 2 weeks should pay close attention to potential side effects, including:

  • Headache

  • Shortness of breath

  • Leg pain/swelling

  • Abdominal pain

If you experience such symptoms in the two weeks after your vaccine, you should contact your health care provider right away.

If I Experience Any Side Effects From the Vaccine, How Do I Report Them?

The public is encouraged to report side effects using a mobile app called v-safeSM. This app uses text messaging to initiate web-based monitoring. Any clinically important event reported by a participant is sent to the Vaccine Adverse Event Reporting System (VAERS), the CDC’s information reporting mechanism. VAERS is considered the nation’s early warning system, giving researchers the first indication that there may be a problem with a particular vaccine.

Why Should I Continue to Take Safety Precautions After I Am Vaccinated?

The vaccine has been shown to protect against symptomatic COVID-19 and against severe COVID-19 disease, but it is not yet known whether someone who has been vaccinated can still acquire and spread COVID-19 to others. So, even if you’ve been vaccinated — it’s still critical to wear a mask, practice physical distancing and observe other precautions until broad public immunity to COVID-19 infection is achieved. Learn more.




What Is Herd Immunity and Why Is It Important?

Herd immunity occurs when 75 - 85% of the whole population is immune to the virus.

How Do I Receive the COVID-19 Vaccine?

COVID-19 infection can have serious and life-threatening complications, and getting the vaccine is the fastest, safest and most effective way to get protected from the disease. In addition, the more people who are vaccinated, the quicker our communities can “return to normal.” The COVID-19 vaccine is free to you. BJC HealthCare and Washington University continue to encourage everyone to get vaccinated.


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