Health Officials Say People Can “Mix & Match” COVID Vaccines

Pfizer and Moderna are recommended over J&J, but people can choose which shot to get based on their individual situation.

Updated on January 10, 2022.

The U.S. Food and Drug Administration (FDA) has authorized boosters of all three COVID-19 vaccines: Pfizer-BioNTech, Moderna, and Johnson & Johnson (J&J). And health officials are urging all fully vaccinated adults to get one once they’re eligible amid an uptick in new cases nationwide and the swift rise of Omicron. New data published on December 23 in Cell indicate that three doses of an mRNA vaccine are more effective than two in protecting against the highly contagious variant, which now accounts for the vast majority of new COVID cases in the United States.

The FDA also used its authority to allow people to mix-and-match, giving adults who are fully vaccinated against COVID-19 the freedom to choose which vaccine they’d like to receive as their booster dose.

So, if you got the J&J shot at least two months ago, you should get a booster dose of either the Pfizer or the Moderna mRNA vaccine, or if you got fully vaccinated with the two-shot Pfizer vaccine at least five months ago, you can choose to get a Moderna shot as your booster dose. And so on. Health officials recommend either Pfizer or Moderna over J&J for most people, due to rare but serious health risks with the J&J vaccine.

The ability to mix and match COVID-19 vaccines offers people more flexibility in getting additional vaccine doses based on what’s available in their local area.

So, which one is best?

Research is ongoing, but the CDC recommends that people get boosted with Pfizer or Moderna. A growing body of evidence suggests that mixing and matching is noy only safe but also produces as many or more antibodies as getting the same vaccine as a booster.

In a preliminary mix-and-match study conducted by the U.S. National Institutes of Health (NIH) that has not yet been published or peer-reviewed, fully vaccinated people who got any of the three available COVID vaccines were given a booster dose of either the Moderna, Pfizer-BioNTech, or J&J vaccine. Overall, there were total of nine different combinations.

The NIH study found that found that people who originally got the Moderna two-dose series and then received any company’s booster saw the biggest increases in neutralizing antibodies against the coronavirus.

But those who got the Moderna booster were given a full dose booster—not a half-dose, which is what has been authorized by the FDA.

The lowest rise was seen in people who got J&J’s vaccine for their initial dose as well as their booster. Those who got the J&J vaccine had a more robust immune system response if they got a booster dose of one of the mRNA vaccines—either Pfizer or Moderna.

Research on the best combinations and how long immunity lasts is ongoing. But, again, federal officials have stated a preference for people to get the mRNA vaccines due to rare but serious side effects with J&J. More research is also needed to examine how long immunity following boosters lasts over time.

Remember, antibodies aren’t everything

Antibody levels, which were investigated in the NIH study, are only one measure of immunity against the coronavirus. The body has other ways of defending itself.

Unlike the innate immune system, which launches a general attack to invading pathogens, the body also has an adaptive, or acquired immune system, which includes two types of cells that learn from experience: T-cells and B-cells. B-cells are antibody factories, while T-cells support B-cells and kill virus-infected cells outright.

Antibody levels may fall after infection. But T-cells and B-cells that the immune system deployed to fight off the infection (or that a vaccine has taught the body to make) can be stored by the immune system for years, where they remain ready to do battle if the virus ever returns.

Article sources open article sources

Centers for Disease Control and Prevention. “CDC Expands COVID-19 Booster Recommendations.” Nov 29, 2021.
U.S. Food and Drug Administration. Coronavirus (COVID-19) Update: FDA Takes Additional Actions on the Use of a Booster Dose for COVID-19 Vaccines. Oct 20, 2021.
Centers for Disease Control and Prevention. "CDC Statement on ACIP Booster Recommendations." Sep 24, 2021.
U.S. Food and Drug Administration. “FDA Authorizes Booster Dose of Pfizer-BioNTech COVID-19 Vaccine for Certain Populations.” Sep 22, 2021.
Centers for Disease Control and Prevention. "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." Aug 13, 2021.
Centers for Disease Control and Prevention. “ACIP Data and Clinical Considerations for Additional Doses in Immunocompromised People.” Jul 22, 2021.
U.S. Food and Drug Administration. “Coronavirus (COVID-19) Update: FDA Authorizes Additional Vaccine Dose for Certain Immunocompromised Individuals.” Aug 12, 2021.
Atmar RL, Lyke KE, Deming ME, et al. Heterologous SARS-CoV-2 Booster Vaccinations – Preliminary Report (preprint). medrXiv. Posted Oct. 13, 2021.
Bar-On YM, Goldberg Y, Mandel M, et al. Protection Across Age Groups of BNT162b2 Vaccine Booster against Covid-19 (preprint). medrXiv. Posted Oct. 7, 2021.
Chiu NC, Chi H, Tu YK, et al. “To mix or not to mix? A rapid systematic review of heterologous prime-boost covid-19 vaccination.” Expert Rev Vaccines. Sep 2021.
Schmidt T, Klemis V, Schub D, et al. “Immunogenicity and reactogenicity of heterologous ChAdOx1 nCoV-19/mRNA vaccination.” Nat Med. 2021 Sep;27(9):1530-1535.
Merck Manual. “Overview of B- and T-Cell Function.” Accessed Oct 19, 2021.
Garcia-Beltran WF, St Denis KJ, Hoelzemer A, et al. mRNA-based COVID-19 vaccine boosters induce neutralizing immunity against SARS-CoV-2 Omicron variant [published online ahead of print, 2022 Jan 6]. Cell. 2022;S0092-8674(21)01496-3.
The White House. “Press Briefing by White House COVID-⁠19 Response Team and Public Health Officials.” Jan. 5, 2022.
Centers for Disease Control and Prevention. “Different COVID-19 Vaccines.” Jan. 7, 2022.
Centers for Disease Control and Prevention. “Johnson & Johnson’s Janssen COVID-19 Vaccine Overview and Safety.” Updated Dec. 28, 2021.

More On

Feeling Anxious? Try These 5 Calming Steps


Feeling Anxious? Try These 5 Calming Steps
Get a handle on stress by making time for these simple mental health habits every day.
How to Help Your Child Transition to Summer


How to Help Your Child Transition to Summer
Graduations and vacations are very different during the pandemic. Here’s advice for helping your family navigate the changes.
COVID-19: Key Terms to Understand Infection and Spread


COVID-19: Key Terms to Understand Infection and Spread
A list of key terms and phrases that are essential to understanding the COVID-19 pandemic.
5 Things The COVID-19 Vaccine Can Prevent


5 Things The COVID-19 Vaccine Can Prevent
A COVID-19 vaccine can prevent you from getting the virus. It can also prevent serious illness from an infection.