COVID Vaccine Booster: Everything You Need to Know

Do You Need a COVID-19 Booster Shot?

Most people who are fully vaccinated against the coronavirus are relatively well-protected from serious illness and death from COVID-19.

But even highly effective vaccines often become less so over time. Early research on vaccines that use mRNA to protect you from the coronavirus, like those from Pfizer and Moderna, suggest that they eventually lose some of their power against infection and serious illness, no matter the variant of the virus (like Alpha, Beta, or Delta). Getting another shot several months after the first round, called a “booster shot,” can help supercharge the vaccine’s effectiveness.

The CDC and FDA both recommend getting a COVID-19 booster shot if you’re eligible. 

Boosters for Pfizer and Moderna Vaccines

Anyone who got the Moderna COVID-19 vaccine at least 6 months ago should get a booster shot if they’re 18 years old or older.

For those who got the Pfizer-BioNTech vaccine, you’re eligible for a booster shot 5 months after your first two doses of the vaccine. The CDC recommends only the Pfizer booster shot for adolescents between 12 to 17 years old. They also should receive the booster shot 5 months after their initial vaccination series. 

Recently, the CDC said there’s a preference for mRNA (Pfizer and Moderna) COVID-19 vaccines over the Johnson & Johnson COVID-19 vaccine. This decision was based on information from the Advisory Committee on Immunization Practices (ACIP). The information discussed vaccine safety, vaccine effectiveness, rare adverse side effects, and U.S. vaccine supply.

While it’s best to get a booster shot from either Pfizer or Moderna, any booster is better than none. If you can only get the Johnson & Johnson booster, you should take it.

Boosters for Johnson & Johnson Vaccine

If you got the Johnson & Johnson vaccine, you should get a booster if you’re 18 or older and got vaccinated 2 or more months ago.

Can You Mix and Match Booster Shots?

Yes. For example, if you got the Moderna vaccine and you prefer to get a Pfizer booster shot, that is perfectly OK, according to the CDC. You can decide if you want to stick with a booster that matches your initial vaccine, or if you want to get one of the other two. (The three vaccines available in the U.S. are Pfizer, Moderna, and Johnson & Johnson.)

Some research suggests mixing vaccines in this way gives as much and perhaps even more protection against COVID-19 infection. 

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What Else Does Research Say About COVID-19 Boosters?

Boosters are just a type of vaccine, and scientists already know that vaccines are currently the best defense against COVID-19, especially its most serious effects. That’s why it’s important to get vaccinated right away if you qualify, as most people 5 and older do.

Research also has found that:

  • In general, antibodies from vaccines decline over time.
  • Higher antibody levels from vaccines seem to make the average person less likely to get sick from the coronavirus (vaccine efficacy).
  • Booster shots of mRNA coronavirus vaccines (Pfizer and Moderna) increase antibodies by about 10 times.
  • Boosters can provide you further protection against the Omicron variant. Early data shows that this variant is more transmissible than other variants.

What if You Have a Weakened Immune System?

The CDC already suggests a third dose of mRNA vaccine for people with weaker immune systems, especially those who are “moderately to severely immunocompromised.” This includes those who are getting cancer treatment, who have had a stem cell or organ transplant, who have advanced or untreated HIV, or who are taking certain medications.

Though not technically a booster shot, many people still call it that.

This extra dose, typically given a month or so after the second dose, is meant to increase the first immune response because:

  • People with weaker immune systems are more likely to have serious, long-term illness from COVID-19.
  • A weaker immune system may not respond as strongly to the vaccine and so may not make enough antibodies to fight off infection and serious illness from COVID-19.
  • Even with a good vaccine response, people with weaker immune systems may benefit from extra protection against COVID-19.

If you have a weakened immune system and have had a third dose of the Pfizer or Moderna vaccine, talk to your doctor about whether you might need a booster shot.

WebMD Medical Reference Reviewed by Brunilda Nazario, MD on January 06, 2022

Sources

SOURCES:

CDC: “CDC Expands Eligibility for COVID-19 Booster Shots,” “COVID-19 Vaccine Booster Shot,” “CDC Statement on ACIP Booster Recommendations,” “Comparative Effectiveness of Moderna, Pfizer-BioNTech, and Janssen (Johnson & Johnson) Vaccines in Preventing COVID-19 Hospitalizations Among Adults Without Immunocompromising Conditions -- United States, March-August 2021,” “Media Statement from CDC Director Rochelle P. Walensky, MD, MPH, on Signing the Advisory Committee on Immunization Practices’ Recommendation for an Additional Dose of an mRNA COVID-19 Vaccine in Moderately to Severely Immunocompromised People,” “COVID-19 Vaccines for Moderately to Severely Immunocompromised People,” “Talking with Patients Who Are Immunocompromised,” “CDC Expands COVID-19 Booster Recommendations to 16-and-17-year-olds,” “CDC Expands COVID-19 Booster Recommendations,” “CDC Endorses ACIP’s Updated COVID-19 Vaccine Recommendations.”  

U.S. Office of the Surgeon General.

Anthony Fauci, MD, director, National Institute of Allergy and Infectious Diseases.

CHEAC.org: “FDA VRBPAC Votes to Recommend COVID-19 Boosters for Older Adults and High-Risk Groups.”

FDA: “Coronavirus (COVID-19) Update: FDA Takes Additional Actions on the Use of a Booster Dose for COVID-19 Vaccines,” “Vaccines and Related Biological Products Advisory Committee Meeting, September 17, 2021.”

Nature: “Mix-and-match COVID vaccines ace the effectiveness test.”

Mayo Clinic: “COVID-19 vaccines for kids: What you need to know.”

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