COVID-19: Booster and Additional Doses

DHS supports the CDC recommendation that anyone 18 and older receive a booster dose of COVID-19 vaccine at least six months after having received their second dose of the Pfizer or Moderna vaccine or two months after their single dose of Johnson & Johnson vaccine. All adults are recommended to receive a booster dose for the best protection against COVID-19. To learn more, read our statement.

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Booster doses and additional doses serve different purposes for different groups of people.

An additional dose is recommended for people who are moderately to severely immunocompromised, because they may not have built enough, or any, protection after the initial series.

In contrast, a booster dose helps boost immune systems for better, longer lasting protection after the strong, initial protection decreases over time.
 

More than 65 million Americans remain unvaccinated, leaving themselves – and their children, families, loved ones, and communities– vulnerable. Please help unvaccinated people take the first step to get an initial COVID-19 vaccine. Vaccination remains the best way to protect yourself, reduce the spread of the virus, and help prevent new variants from emerging.

Booster doses

A “booster dose” is a supplemental vaccine dose given to people when the immune response to a primary vaccine series is likely to have decreased over time. The primary COVID-19 vaccination series continues to be highly effective at reducing severe disease, hospitalization, and death caused by COVID-19. However, experts are starting to see that protection against mild to moderate disease can fade over time. The booster dose is intended to boost your immune system for better, long lasting protection.

Safety data from other countries and the Centers for Disease Control and Prevention (CDC) shows that booster and additional doses are safe. Side effects, which are expected with vaccination, were mostly mild, moderate, and lasted only a few days, similar to the last dose of the primary series. For Pfizer-BioNTech and Moderna, side effects were reported less frequently following a booster dose than the second dose of the primary series.

Who can get a booster dose?

Everyone ages 18 and older is recommended to get a booster dose for the best protection against COVID-19 and circulating variants.

Booster doses are strongly recommended for people who are at the greatest risk for severe disease, such as people who are 18 years and older and live in a long-term care setting and everyone 50 years and older.

If you are 18 years or older, you can get your COVID-19 booster dose:

  • At least 6 months after you got your last dose of your Pfizer or Moderna primary vaccine series.
  • At least 2 months after you got your Johnson & Johnson COVID-19 vaccine.

You can choose which vaccine you get as a booster dose, no matter which vaccine you got in your primary series.

While vaccination remains the most effective tool we have to prevent COVID-19, everyone should continue to practice good public health behavior. This means wearing a mask indoors, avoiding large gatherings, staying home when feeling sick, and getting testing if you have symptoms or after close contact.


Additional doses

An “additional dose” is recommended for people who may not have received adequate protection from their initial vaccine series. On August 13, the FDA updated the emergency use authorizations (EUAs) for the Pfizer and Moderna COVID-19 vaccines to allow for additional doses to very specific groups of people. Eligible people can get an additional mRNA dose at any time, as long as it is at least 28 days after completing the initial two-dose mRNA COVID-19 vaccine series (such as for Pfizer and Moderna).

Who should get an additional dose?

Individuals with specific medical conditions or receiving medical treatments that cause them to be moderately to severely immunocompromised are recommended to get an additional dose of Pfizer or Moderna COVID-19 vaccine. Immunocompromised people have a reduced ability to fight disease, a lower immune response to the original vaccine series compared to other fully vaccinated people, and are especially vulnerable to COVID-19 infection. 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 two 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, alkylating agents, antimetabolites, transplant-related immunosuppressive drugs, cancer chemotherapeutic agents classified as severely immunosuppressive, tumor-necrosis (TNF) blockers, or other drugs that may suppress your immune response.

Even though the additional dose will be important to help prevent COVID-19 hospitalizations and death, immunocompromised people may still have a reduced immune response after getting the additional dose of the mRNA COVID-19 vaccine. This means it is still important for immunocompromised people to continue to follow current prevention measures (like wearing a mask and physical distancing) even after their additional mRNA COVID-19 vaccine dose.

Talk to your health care provider about:

  • whether you need to get an additional dose.
  • whether you will need to pause your treatment or medication before or after getting an additional dose of the vaccine.

If you don't have a health care provider, call 211 or text COVID to 211-211. Language assistance is available.

 

Frequently asked questions about additional doses and booster doses

What data is the booster dose recommendation based on?

The CDC's independent Advisory Committee on Immunization Practices (ACIP)’s booster dose recommendation followed a careful examination of the latest data, and robust and deliberative discussion around booster shots. This includes:

  • Safety: CDC’s vaccine safety monitoring systems show that reported side effects, which are expected with vaccination, have so far been mostly mild or moderate, and short-lived. For both Pfizer-BioNTech and Moderna, side effects were reported less frequently following a booster dose than the second dose of the primary series. Regardless of manufacturer, more than 93 percent of reports to VAERS following COVID-19 booster dose vaccination have been non-serious.
  • Vaccine effectiveness: Data show that vaccine effectiveness against COVID-19 infection is waning after the vaccine primary series, but protection remains high against severe disease and hospitalization. Administration of a booster shot may result in increases in antibody levels and increased effectiveness compared to primary vaccination.

The balance of risks and benefits for booster doses of an mRNA COVID-19 vaccine varies by age, with older adults benefiting the most from a booster shot. However, with the emergence of new SARS-CoV-2 variants, the CDC recommends that everyone ages 18 and older get a booster shot when eligible for the best protection against COVID-19. 

Do additional doses and booster doses have the same dose sizes and ingredients as the primary COVID-19 vaccine series?

The booster doses and additional doses are all the same vaccines that are used for primary series. The Pfizer and Johnson & Johnson booster doses use the same dosage as the primary series, while the Moderna booster dose uses a half dose. Both Moderna and Pfizer additional doses use the same dosage as the primary series.

Do I need to receive a booster or additional dose to be considered fully vaccinated?

No, people are considered fully vaccinated two weeks after you’ve received either a single-dose vaccine, like Johnson & Johnson, or the second dose of a two-dose vaccine, like Pfizer or Moderna.

Do booster doses and additional doses mean that COVID-19 vaccines aren’t working?

No. COVID-19 vaccines are working well to prevent severe disease, hospitalization, and death. However, public health experts are starting to see reduced protection, especially among certain populations, against mild and moderate disease.

Even with the SARS-CoV-2 variants circulating, and vaccines decreasing in effectiveness over time for some groups, fully vaccinated people are much less likely to get sick or spread the disease than not fully vaccinated people.

Vaccination remains the best way to protect yourself and reduce the spread of the virus and help prevent new and potentially more dangerous variants from emerging.

Is it safe to get a COVID-19 booster or additional dose with other vaccines, like the flu vaccine?

Yes, it is safe to get a COVID-19 vaccine, primary series, booster dose, or additional dose, at the same time as other vaccines.

Are booster and additional doses also free?

Yes, COVID-19 vaccines, including booster doses and additional doses, are free for everyone. You do not need an ID or insurance to get it. Vaccines will continue to be given to all people living in the United States, regardless of insurance or immigration status.

What should immunocompromised people who received the Johnson & Johnson (Janssen) COVID-19 vaccine do?

Everyone who got the Johnson & Johnson COVID-19 vaccine and is 18 years and older is recommended to get a booster dose. Eligible individuals may choose which vaccine they receive as a booster dose – Johnson & Johnson, Moderna, or Pfizer.

Can you mix and match the COVID-19 vaccines?

Yes, CDC’s recommendations now allow for mix and match dosing for booster doses. Eligible individuals may choose which vaccine they receive as a booster dose – Moderna, Johnson & Johnson, or Pfizer. Some people may have a preference for the vaccine type that they originally received and others may prefer to get a different booster.

The additional dose should be the same vaccine product as the initial two-dose mRNA COVID-19 vaccine series (Pfizer or Moderna). If you are 18 years or older and the mRNA COVID-19 vaccine product given for the first two doses is not available, you can get the other mRNA COVID-19 vaccine product that is available.

For example, if you received your first two doses of Pfizer COVID-19 vaccine but you cannot find a vaccine location that has Pfizer vaccine, you can get an additional dose of Moderna COVID-19 vaccine if you are 18 years or older. If you are immunocompromised and are younger than 18 years old, your additional dose has to be a dose of Pfizer COVID-19 vaccine.

Can I get a booster dose after getting an additional dose?

Yes, people 18 years and older who are moderately and severely immunocompromised may receive a booster dose six months after they received an additional mRNA vaccine dose.

If you are immunocompromised and initially received two doses of an mRNA series (Pfizer or Moderna), you can get:

  • One additional mRNA dose at least 28 days after the second dose of your initial COVID-19 vaccine series.
  • One booster dose at least six months after your additional mRNA dose.

If you are immunocompromised and initially received one dose of Johnson & Johnson, you should get:

  • One booster dose (either Pfizer, Moderna, or Johnson & Johnson) at least two months after your initial Johnson & Johnson dose.

Where can I get an additional dose or a booster dose?

You can get an additional dose or booster dose wherever COVID-19 vaccines are offered. Visit vaccines.gov, text your zip code to 438829, or call 211 to find vaccine locations near you. If you are getting an additional dose, try to make sure the vaccination location has the same kind of vaccine you received for your first two doses.

If possible, bring your white CDC COVID-19 vaccination card or a printed or downloaded summary of your immunization record.


Resources about booster and additional doses


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Last Revised: November 30, 2021

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