A COVID booster shot is an additional dose of a vaccine given after the protection provided by the original shot(s) has begun to decrease over time. Typically, you would get a booster after the immunity from the initial dose(s) naturally starts to wane. The booster is designed to help people maintain their level of immunity for longer.
The CDC recommends a COVID-19 booster if you are:
Individuals who have a medical condition associated with immunosuppression are eligible to receive an additional vaccine dose.
Please visit the CDC website for the latest information on vaccine boosters.
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.
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.
An additional dose, originally called a third dose, is given to people with moderately or severely compromised immune systems to improve their response to the initial vaccine series. (The term “third dose” was used to refer to additional doses for the two mRNA vaccines, but now the term is “additional dose” because those who received a J&J “one dose” may also be eligible for a dose based on their immune systems.)
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.
The CDC and the FDA recommend an additional dose if you:
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.
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 2 months since your vaccine.
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.
The Pfizer-BioNTech vaccine is the only vaccine and booster authorized for individuals ages 16 and 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.