The Food and Drug Administration (FDA) issued emergency use authorizations (EUA) for Moderna and Johnson & Johnson COVID-19 booster shots on Wednesday. And, with that, FDA officials will officially also allow Americans to mix and match their booster doses, in what’s known to the medical community as heterologous boosters. Meaning, if you wanted to, you could get a booster shot that’s different from the original COVID-19 vaccine you received.
FDA officials did not recommend that people get one vaccine over another, and also did not state that sticking with the same vaccine for your booster is the way to go.
The emergency use authorizations for the Moderna and Johnson & Johnson boosters join the Pfizer-BioNTech COVID-19 vaccine, which was authorized by the FDA last month in the U.S. to be used as a booster shot.
From here, the FDA will send the data over to the Centers for Disease Control and Prevention’s (CDC) Advisory Committee on Immunization Practices, which will finalize how the booster should be used and by whom. Only after that has happened, will eligible people be able to receive Moderna and Johnson & Johnson boosters.
Here’s what you need to know about mixing and matching booster doses, plus whether or not this is something you should consider.
Who is eligible for COVID-19 booster doses again?
Recommendations differ slightly by vaccine.
The Pfizer-BioNTech COVID-19 vaccine is authorized for booster doses in the U.S., and only to select groups. These are the people who currently qualify for a Pfizer booster dose at least six months after their original vaccination series, according to the CDC:
65 years and older
Age 18+ who live in long-term care settings
Age 18+ who have underlying medical conditions
Age 18+ who live or work in high-risk settings
Again, the Moderna and Johnson & Johnson boosters haven’t gone through the ACIP yet, but these are the FDA’s recommendations for eligibility.
The FDA recommends that the following groups of people get a Moderna booster dose after at least six months after their original vaccination series:
65 years of age and older
18 through 64 years of age at high risk of severe COVID-19
18 through 64 years of age who live and work in a place where they’re frequently exposed to COVID-19
Johnson & Johnson
The FDA recommends that people who are at least 18 receive a Johnson & Johnson booster at least two months after they received their first dose.
What does the data say?
When the FDA expert advisory committee met late last week to discuss the merits of the Moderna and Johnson & Johnson booster shots, they analyzed data from a study that found people who received a Moderna booster after the Johnson & Johnson vaccine saw antibody levels against SARS-CoV-2, the virus that causes COVID-19, rise 76-fold in 15 days. By comparison, there was only a fourfold increase after they received a Johnson & Johnson booster.
The FDA also cited more details in its emergency use authorization announcement. According to the FDA, officials analyzed data for Moderna from 149 participants who are 18 and up who received a booster dose at least six months after their second dose and compared it to 1,055 study participants after they completed their two-dose series. Twenty-nine days after receiving their booster dose, the 149 participants “demonstrated a booster response,” the FDA said. (While the FDA didn’t specify exactly what they were measuring, demonstrating a booster response means that the boosters caused an increase in antibody levels to SARS-CoV-2, the virus that causes COVID-19, explains infectious disease expert Amesh A. Adalja, M.D., senior scholar at the Johns Hopkins Center for Health Security.)
The FDA also evaluated an analysis from Moderna that compared the rates of COVID-19 in vaccinated people during the Delta variant surge during July and August 2021, suggesting that the vaccine’s effectiveness waned over time.
The FDA shared data for its emergency use authorization for the Johnson & Johnson vaccine, noting that they analyzed information from 39 people who received a booster dose about two months after their initial dose. “The results demonstrated a booster response,” the FDA said. Overall, about 9,000 clinical trial participants have had two doses of the Johnson & Johnson vaccine, per the FDA, and about 2,700 of those have had at least two months of safety follow-up, which have not identified any new safety concerns.
All of the data was based on a small group of volunteers and long-term data isn’t available. But experts say it definitely makes the case for mixing and matching boosters.
“There has always been interest in what is known as heterologous prime boost strategies using vaccines that represent distinct technologies,” Dr. Adalja says. “Early data has shown that this may be a more beneficial approach when mRNA vaccines follow the Johnson & Johnson or AstraZeneca vaccines.”
“The data would indicate that you get a very powerful large antibody response,” points out William Schaffner, M.D., an infectious disease specialist and professor at the Vanderbilt University School of Medicine.
So, should you mix and match booster shots?
Dr. Schaffner stresses that there is no official word from the CDC just yet. Still, he says, “There will be many infectious disease physicians and public health personnel who will be recommending to previous Johnson & Johnson recipients that they get a Moderna or Pfizer vaccine as a follow-up.”
Thomas Russo, M.D., professor and chief of infectious disease at the University at Buffalo in New York, agrees that an mRNA booster like Pfizer or Moderna seems to be a better bet for most people, regardless of their first vaccine series. “As a general rule what I’m recommending is, if you had Johnson & Johnson, you should get an mRNA booster,” he says. The only exception, Dr. Russo says, is with people who have a history of myocarditis, an inflammatory heart condition. “If someone has a history of myocarditis and they received the Johnson & Johnson vaccine initially, that is a relative contraindication for getting an mRNA vaccine booster,” he says.
If you had an original Moderna or Pfizer vaccine series, you could technically get a different booster, but there’s not necessarily compelling data to go this route, Dr. Schaffner says. Dr. Adalja agrees. “I do not think there’s much value in people mixing and matching vaccines that use the same technology such as the Pfizer and Moderna vaccines,” he says.
But, “it seems to be a good one-two punch to follow the Johnson & Johnson vaccine with a Moderna or Pfizer booster,” Dr. Schaffner says.
Getting any booster dose if you’re eligible is important to keep up your protection against COVID-19, says Richard Watkins, M.D., an infectious disease physician in Akron, Ohio, and a professor of internal medicine at the Northeast Ohio Medical University. But, if you had Johnson & Johnson in the past, he also recommends following it up with a different vaccine. “If I had a choice, I’d pick either the Moderna or Pfizer mRNA vaccines as a booster for the Johnson & Johnson due to higher levels of antibodies that result,” he says.
Is there any reason not to do this?
While experts agree that the data suggest that mixing and matching vaccines is OK to do and may even be a good idea if you had the Johnson & Johnson vaccine to start, Dr. Schaffner recommends being mindful of your allergies. If you have a known allergy, he suggests looking up the ingredients in the vaccine you’re interested in getting, just to make sure there aren’t any potential issues.
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