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September 27, 2021

What should I expect after getting a COVID-19 vaccine?

The answers on this site were developed with and vetted by the CDC

You may have short-term side effects after vaccination. These are normal and should go away in a few days.

You may feel soreness or experience some swelling in your arm. You may also feel tired, have a headache, fever, or chills. These symptoms do not mean you have COVID-19 — it’s not possible to get COVID-19 from the vaccine.

These side effects may impact your daily activities, but they shouldn’t last more than 2-3 days. If they continue or get worse, call your doctor, nurse, or clinic.

Even if you have these types of effects after your first shot, it’s important to make sure you get the second one, unless a vaccination provider or your doctor tells you not to get a second shot or you get the vaccine that only requires one dose. Ask your doctor if you have questions. Your body takes time to build immunity. You will not be fully protected against COVID-19 until 1-2 weeks after your final shot.

In most cases, discomfort from fever or pain is normal. Contact your doctor or healthcare provider:

  • If the redness or tenderness where you got the shot increases after 24 hours

  • If your side effects are worrying you or do not seem to be going away after a few days

  • If you develop severe headache, abdominal pain, leg pain, or shortness of breath within the first three weeks.

  • 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. Learn more about COVID-19 vaccines and rare severe allergic reactions.

Dr. Oronsaye - How Will I Feel Afterwards | COVID-19 Vaccine Education Initiative
What to expect after the vaccine (CDC)

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Could I have an allergic reaction?

Severe allergic reactions to vaccines are extremely rare. The FDA says the authorized COVID-19 vaccines appear to be safe for people with common food or environmental allergies.

CDC recommends that people get vaccinated even if they have a history of severe allergic reactions not related to vaccines or injectable therapies—such as food, pet, venom, environmental, or latex allergies. People with a history of allergies to oral medications or a family history of severe allergic reactions may also get vaccinated.

If you have had an immediate allergic reaction — even if it was not severe — to a vaccine or injectable therapy for another disease, ask your doctor if you should get a COVID-19 vaccine. Your doctor will help you decide if it is safe for you to get vaccinated.

All people who get a COVID-19 vaccine should be monitored on site. People who have had any type of severe or immediate allergic reaction in the past should be monitored for at least 30 minutes after getting the vaccine. All other people should be monitored for at least 15 minutes after getting the vaccine.

More about adverse effects (CDC)
Should I worry about long-term side effects?

It is extremely unlikely you will suffer serious side effects that could cause a long-term health problem after getting a COVID-19 vaccine.

Long-term side effects following any vaccination are extremely rare. In the past vaccine monitoring has shown that if side effects are going to happen, they tend to happen within six weeks of receiving a vaccine dose.

For this reason, the FDA required each of the authorized COVID-19 vaccines to be studied for at least eight weeks after the final dose. Millions of people have received COVID-19 vaccines, and no long-term side effects have been found.

The CDC continues to closely monitor COVID-19 vaccines for any safety issues, including problems with manufacturing, a specific lot, or the vaccine itself. If public health experts find any potential safety concerns, FDA and the vaccine manufacturer will work towards a solution.

Safety of COVID-19 Vaccines (CDC)
What should I know about the Johnson and Johnson vaccine?

After pausing the use of Johnson & Johnson’s Janssen COVID-19 Vaccine, the CDC and FDA have recommended that it should once more be used in the United States.

The data we have suggest that the chance of severe adverse reactions such as blood clots with low platelets is very small. However, women younger than 50 years old should be aware of the rare risk of blood clots with low platelets after getting Johnson & Johnson’s Janssen vaccine.

There have been no reports of blood clots with low platelets with the Pfizer-BioNTech or Moderna vaccines. More than 332 million doses of those vaccines have already been given in the United States.

COVID-19 vaccines have undergone the most intensive safety monitoring in U.S. history. They will continue to be watched closely. COVID-19 vaccine safety is a top priority for the federal government. All reports of health problems following COVID-19 vaccination are taken very seriously.

Johnson & Johnson’s Janssen COVID-19 Vaccine Overview and Safety (CDC)
Will I need a COVID-19 booster shot?

CDC currently recommends that people who have moderately or severely compromised immune systems should receive an additional dose of mRNA COVID-19 vaccine (Moderna or Pfizer) after the initial 2 doses. This is because people with compromised immune systems may not build the same level of immunity to 2-dose vaccine series compared to people who are not immunocompromised.

In September 2021, the FDA and CDC also authorized a booster shot of the Pfizer COVID-19 Vaccine (Comirnaty) for certain other groups. For these groups, the booster shot must be administered at least six months after an individual has already completed the primary series (dose 1 and 2). These eligible groups include:

  • People 65 years of age or older

  • People aged 18–49 years with underlying medical conditions

  • People aged 18–64 years at increased risk for COVID-19 exposure and transmission because of their job or because they are in a long-term care setting

Please click here for full detail on who is currently eligible to receive a Pfizer booster shot. For certain groups, CDC suggests that people talk to their healthcare provider about whether getting a Pfizer-BioNTech COVID-19 booster shot is appropriate for them. This authorization applies only to the Pfizer-BioNTech COVID-19 Vaccine. FDA and CDC are actively working to determine further guidance for individuals who received the Moderna or Johnson & Johnson vaccines.

Public health experts are also still recommending immunocompromised people take precautions like staying six feet away from others to avoid catching COVID-19. Those who are close to immunocompromised people are strongly advised to get vaccinated, if their health allows, to protect their loved ones.

This page will continue to be updated as public health experts have more information.

COVID-19 Vaccines for Moderately to Severely Immunocompromised People (CDC)
Can COVID-19 vaccines lead to heart inflammation in adults?

There have been a small number of reported cases of heart inflammation following a COVID-19 vaccine. Myocarditis is inflammation of the heart muscle. Pericarditis is inflammation of the outer lining of the heart. Incidents have mostly been reported among male adolescents and young adults who have received an mRNA vaccine. Among the hundreds of millions of vaccine doses given, these reports are rare.

Symptoms of these rare cases included chest pain, shortness of breath, or feelings of having a fast-beating, fluttering, or pounding heart. Most patients with myocarditis who received care responded well to treatment and rest and quickly felt better.

CDC continues to advise that the known and potential benefits of COVID-19 vaccination outweigh the known and potential risks.

Myocarditis and Pericarditis Following mRNA COVID-19 Vaccination (CDC)

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