Health
a health care provider prepares a vaccine for a mature woman
a health care provider prepares a vaccine for a mature woman
a health care provider prepares a vaccine for a mature woman

Booster Shots and Additional Doses for COVID-19 Vaccines — What You Need to Know

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Updated April 8, 2022

The CDC has approved a second COVID-19 booster for people age 50 and older that can be given 4 months after a first booster. People with moderate to severe immunosuppression are also eligible to receive an additional shot.

The CDC has also approved a second COVID-19 mRNA booster (Pfizer or Moderna) for people who received the Johnson & Johnson vaccine and booster. The second booster can be given 4 months after the first booster. Visit the CDC for more information on this expanded eligibility.

Lisa Maragakis, M.D., M.P.H., senior director of infection prevention, and Gabor Kelen, M.D., director of the Johns Hopkins Office of Critical Event Preparedness and Response, explain what you need to know about these COVID shots.

What is a COVID-19 vaccine booster?

A COVID booster shot is an additional dose or doses of a vaccine given after the protection provided by the original shot(s) has begun to decrease over time. The booster helps people maintain strong protection from severe coronavirus disease.

Who can get a COVID-19 vaccine booster? Who can get a second COVID-19 booster?

The CDC recommends an initial COVID-19 booster if you are:

  • Age 18 or older and you received the Janssen-Johnson & Johnson vaccine at least two months ago
  • Age 18 or older and you received both required doses of the Moderna vaccine at least five months ago (your booster will be a one-half dose)
  • Age 12 or older and you received both required doses of the Pfizer-BioNTech vaccine at least five months ago (the Pfizer-BioNTech vaccine is the only vaccine and booster authorized for children and teens ages 12–17)
  • The CDC recommends that you get vaccinated and boosted even if you previously had COVID-19 infection. Before getting a shot, be sure you have followed isolation and quarantine guidelines so you do not infect others, and discuss your COVID-19 history with the medical team.

As of March 30, 2022, the CDC expanded eligibility for a second booster for those:

  • age 50 or older who received a first COVID-19 booster at least 4 months ago.
  • Anyone who received Janssen/Johnson & Johnson for their COVID-19 vaccine and/or booster dose. A second mRNA booster can be given four months after the first booster.
  • Individuals age 12 or older who are moderately to severely immunosuppressed are eligible for an additional booster.

Visit the CDC’s website for more information on these recommendations.

Can children get a COVID-19 booster?

Yes, the CDC recommends that children and teens age 12 and older receive a booster when eligible. Since the Pfizer vaccine is currently the only authorized vaccine for those under age 18, children 12 and older should receive a booster five months after their second Pfizer shot.

Children age 5 and older who have certain medical conditions associated with immunosuppression can receive an additional dose 28 days after their second dose.

Please visit the CDC website for the latest information on vaccine boosters.

What are COVID booster side effects?

After getting vaccinated for COVID-19, you might experience some temporary symptoms similar to those you might notice when you get a flu shot, such as a sore, swollen arm where you got the shot. You might run a fever and experience body aches, headaches and tiredness for a day or two. Chills, swollen lymph nodes can also occur.

These symptoms do not mean you are sick. They signal that your immune system is responding to the shots and building up protection against the coronavirus.

Where can I get a COVID-19 vaccine booster?

Please check your state or local resources. Retail pharmacies, mobile vaccination clinics (walk-up) and state and local vaccination sites offer booster appointments. Some locations may offer walk-up vaccination times.

Johns Hopkins Medicine has limited booster/additional dose appointments at some of its Maryland locations.

Should I get an additional COVID-19 vaccine dose if I have a weakened immune system?

Yes, the CDC has approved an additional dose for individuals ages 12 and older who are moderately to severely immunosuppressed. Visit the CDC’s website for additional eligibility information for those who are moderately to severely immunosuppressed.

What is the difference between a booster and an additional dose?

A COVID-19 booster is given when a person has completed their vaccine series, and protection against the virus has decreased over time. Depending on the original series you had, some details will vary. Please review the booster eligibility information above and talk to your health care provider if you are not sure if you meet these guidelines. Please note, if you receive the Moderna booster, you will receive half of the original Moderna dose.

An additional dose is administered to people with moderately to severely compromised immune systems. This additional dose is intended to improve immunocompromised people’s response to their initial vaccine series. Depending on the original series given, some details will vary. Please review the additional dose eligibility information and talk to your health care provider if you are not sure if you meet these guidelines.

Who can get an additional dose of a COVID-19 vaccine?

Depending on the age of the person who is immunocompromised, the CDC recommends an additional dose or doses.

If you are not sure whether you fit into any of these categories, please contact your medical provider. For more details, please review the CDC’s information for moderately to severely immunocompromised people.

When should I get an additional dose of COVID-19 vaccine?

If you are immunosuppressed and originally received the Moderna or Pfizer COVID-19 vaccine, you can get an additional dose when it has been at least 28 days since your second shot.

If you got the Janssen/Johnson & Johnson COVID-19 vaccine, you can get an additional dose when it has been at least two months since your vaccine.

Does my COVID-19 booster or additional dose have to be the same brand that I got before?

No, you can mix and match brands. The FDA has authorized three vaccine boosters — Pfizer-BioNTech, Moderna and Janssen-Johnson & Johnson — and determined that it is safe to get a COVID-19 vaccine booster or additional dose that is a different brand than your initial dose or doses. 

As of March 30, 2022, the CDC has approved anyone who received Janssen/Johnson & Johnson for their COVID-19 vaccine and/or booster dose to get a booster of either the Pfizer or Moderna mRNA COVID-19 vaccines. A second booster can be given four months after the first booster.

The Pfizer-BioNTech vaccine and booster are the only ones authorized for children and teens ages 12–17.

If you get the Moderna booster, you will receive half of the original Moderna dose. Please be sure to confirm this with the person giving you the shot.

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COVID-19 Vaccine

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