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July 23, 2021

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

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

It’s normal to experience some mild discomfort following a vaccine. This means it’s working and creating an immune response in your body.

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 medications—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 severe allergic reactions or who have had any type of immediate allergic reaction to a vaccine or injectable therapy 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?

Serious side effects that would cause a long-term health problem are extremely unlikely following COVID-19 vaccination.

Long-term side effects following any vaccination are extremely rare. Vaccine monitoring has historically shown that if side effects are going to happen, 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 eight weeks after the final dose. Millions of people have received COVID-19 vaccines, and no long-term side effects have been detected.

More on the safety of vaccines
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 the use of Johnson & Johnson vaccine resume in the United States. Check here for the latest information.

At this time, the available data suggest that the chance of severe adverse reactions such as rare blood clots with low platelets is very low. However, women younger than 50 years old should be aware of the rare risk of blood clots with low platelets after receiving the Johnson & Johnson/Janssen vaccine.

This risk has not been seen with other COVID-19 vaccines that are available.

No reports of blood clots with low platelets have been reported with the Pfizer-BioNTech or Moderna vaccines, with more than 332 million doses of those vaccines already having been administered in the United States.

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

More about adverse effects (CDC)
Will I need a COVID-19 booster shot?

Getting vaccinated against COVID-19 will help protect you for the near future, but it’s still not clear how long protection will last. We don’t yet know whether COVID-19 booster shots will be needed, or at what intervals.

CDC is updating guidelines as they learn more about how long vaccines protect against COVID-19 in real-world conditions. We will continue to update this page as we hear more from public health experts.

Vaccine FAQs for Healthcare Professionals (CDC)