Although your initial COVID-19 vaccination was effective in preventing severe illness, studies are showing that the vaccines' protection can decrease over time.

Health experts are starting to see reduced protection against mild and moderate disease among certain groups of people, such as those over the age of 65.

This is why the Centers for Disease Control (CDC) says all people should be up to date with their vaccinations. For example, all vaccinated people age 18 and older should get their booster doses as soon as they are eligible. Older adults and people with immunocompromising conditions are more likely to get severe COVID. The CDC now recommends a booster dose for children age 12-17.

In addition to the first booster dose, the CDC has now made a second booster of either the Pfizer or Moderna vaccine available to people over the age of 50 and some others. Learn more about what the CDC says about who can and should get a COVID booster.

Ready for your booster? Find out where to get a booster in Maryland.

Getting a booster shot as soon as you are eligible after your initial vaccine series is critical to maintaining your protection against the virus and help prevent the further spread of the virus among those who are unvaccinated, such as children under age 5.

"Being the most updated with your COVID-19 vaccination remains the best way to protect yourself against the virus and its variants. We recommend that you complete your booster dose as soon as you are eligible, to optimize your immunity," says Wilbur Chen, MD, MS, professor of medicine at the University of Maryland School of Medicine (UMSOM) and an adult infectious disease expert in the school's Center for Vaccine Development and Global Health (CVD).

Who's Eligible for a COVID-19 Booster Shot?

The CDC recommends that everyone ages 12 and older get a COVID-19 booster shot as soon as they are eligible. Children ages 12 to 17 can get only the Pfizer-BioNTech booster, at least five months after their second shot.

If you are 18 years of age or older, you can choose whichever approved vaccine (Pfizer-BioNTech, Moderna or Johnson & Johnson) you want to receive as your booster, even if it wasn't your original vaccine (you can mix and match).

The CDC advises a preference for an mRNA COVID-19 vaccine over the Johnson & Johnson COVID-19 Vaccine for booster vaccination.

People should get their booster shot:

  • At least five months after getting both shots of Pfizer-BioNTech or Moderna
  • At least two months after getting the single Johnson & Johnson shot

Second boosters of Pfizer and Moderna shots are available four months after your first booster to:

Schedule Your Booster Shot

If you are eligible for a booster, please visit the official COVID-19 vaccination page on to learn more about how you can schedule your booster shot appointment.

Make sure to bring your COVID-19 Vaccination Record card to your appointment so your provider can add information about your booster dose to it. If do not have your card, learn more about how to get a vaccine card replacement in Maryland.

Is the Booster Shot Safe?

Booster shots are proven to be safe.

As with the initial two-shot or single-dose vaccine shots, serious side effects are rare. So far, reactions reported after the booster shot have been similar to those after the first vaccination series, according to the Centers for Disease Control and Prevention (CDC). Overall, side effects have been mostly mild to moderate, the CDC says.

Side effects are normal signs that your body is building protection against COVID-19.

Are You Still Fully Protected Without a Booster Shot?

You are still considered vaccinated two weeks after your second dose of Pfizer-BioNTech or Moderna or two weeks after your single-dose shot of the Johnson & Johnson's Janssen vaccine.

However, the booster shot is ";intended to continue to provide you with the best protection against this pandemic," particularly the variants, Chen says. "It's super important to keep updated with your vaccination by completing your booster dose as soon as you are eligible for it."

Does the Booster Work Against Recent Variants?

Data suggest that in the early part of 2021 the Omicron strain was spreading faster than any other COVID-19 variant before it. Omicron first appeared in the United States on December 1, 2021. By January 1, 2022, the CDC reported that Omicron represented 95 percent of new infections in the United States.

Data from recent clinical trials showed that a booster shot increased the immune response to the variant in participants who had been fully vaccinated with Pfizer-BioNTech or Moderna vaccine six months earlier or Johnson & Johnson two months earlier. Additionally, clinical trials demonstrated that a booster can help prevent COVID-19 with symptoms.

Is an Additional Dose for Immunocompromised People the Same as a Booster?

An additional dose of your primary vaccine series for people who are immunocompromised is not the same as a booster shot. If you are immunocompromised and receive an additional dose (e.g., third dose of mRNA vaccine), you should still get a booster dose of the COVID-19 vaccine at a recommended interval.

The Centers for Disease Control recommends that people age 5 and older who are moderately to severely immunocompromised receive an additional dose (third dose) of an mRNA COVID-19 vaccine at least 28 days after the second dose of either the Pfizer or Moderna vaccine. For children 5-17, only the Pfizer vaccine is authorized.

Unlike with a booster, you should receive the additional dose (third dose) with the same vaccine as your initial two doses of vaccine.

This additional dose of is only for people who are immunocompromised as outlined in the CDC's recommendations. This includes people who have:

  • Been receiving active cancer treatment for tumors or cancers of the blood
  • Received an organ transplant and are taking medicine to suppress the immune system.
  • Received a stem cell transplant within the last 2 years or are taking medicine to suppress the immune system.
  • Moderate or severe primary immunodeficiency (such as DiGeorge syndrome, Wiskott-Aldrich syndrome).
  • Advanced or untreated HIV infection.
  • Active treatment with high-dose corticosteroids or other drugs that may suppress your immune response.

Please talk to your doctor about whether this additional dose is appropriate for you.

Updated 3/4/2022

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