FDA Backs Moderna and J&J Boosters, Plus Mix-and-Match Strategy

Experts say fully vaccinated Americans are still well protected, but boosters could provide added immunity for millions

Photo of Black woman receiving a vaccine from a doctor with a bandaid on her arm
Since the country’s first booster shot was approved last month, some 11.6 million individuals have received the additional jab. LPETTET via Getty Images

This week the Centers for Disease Control and Prevention endorsed booster shots of the mRNA-based Moderna and the one-shot Johnson & Johnson Covid-19 vaccines for tens of millions of individuals. The decision is hailed as a victory for the Biden administration, which has been eager to expand booster eligibility following the agency’s endorsement of the Pfizer-BioNTech booster last month. Officials also stated that those who received the Moderna or Johnson & Johnson vaccine can opt for a different brand than their initial dose, formally allowing “mixing and matching” of boosters.

“Today’s actions demonstrate our commitment to public health in proactively fighting against the Covid-19 pandemic,” said the FDA's acting commissioner, Janet Woodcock. She acknowledged data suggest waning immunity in some populations and said “the availability of these authorized boosters is important for continued protection against Covid-19 disease.”

The recent announcement expands booster options to all three approved vaccines in the United States. The agency hopes approving a mix-and-match strategy for Covid-19 boosters will make it simpler for Americans to get another vaccine, and provides a choice for those who had initial side effects and want to switch brands. Since the first booster shot was approved last month, some 11.6 million individuals have received the additional jab, report Manas Mishra and Julie Steenhuysen for Reuters.

Higher-risk Americans who received Pfizer-BioNTech or Moderna vaccines are eligible for a booster shot 6 months after the initial round of inoculations. The group of eligible recipients includes individuals over 65 years of age, those with underlying medical conditions and individuals who live or work in high-risk settings, like first responders, educators and public transit workers. For the roughly 15 million Americans who got the Johnson & Johnson Covid-19 vaccine, booster shots are recommended for those 18 and older who were vaccinated at least two months ago. The advisory committee also noted early evidence suggesting that Johnson & Johnson vaccine recipients can more effectively boost antibody levels by switching to one of the two mRNA vaccines from Moderna or Pfizer.

“Being able to interchange these vaccines is a good thing—it’s like what we do with flu vaccines,” said Peter Marks, director of the Center for Biologics Evaluation and Research at the FDA, Wednesday evening. “Most people don’t know what brand of flu vaccine they received.” 

One notable change is that Moderna’s booster shot will be a smaller dose than the original version—just 50 micrograms, which is half the dose given in the initial rounds of immunization, report Matthew Perrone and Lauren Neergaard for the Associated Press. The company said their smaller dose reduces the risk of side effects but is still enough to prompt a robust immune response.

Though Covid-19 cases are slowly decreasing in most areas of the country, there are still about 75,000 new cases every day, and around 1,500 deaths. The recent CDC announcement surprised and angered some experts who say there’s not yet enough scientific evidence to determine whether boosters were actually necessary for most individuals, according to Apoorva Mandavilli for the New York Times. The panel of scientists noted that through the Pfizer and Moderna vaccines are generally safe, there is a rare risk of heart inflammation, called myocarditis, in young adult men, and the Johnson & Johnson vaccine carries a small risk of blood clots in young women.

Some CDC scientists noted that the minor risk of these complications may outweigh the benefit of getting a booster for those that are already fully vaccinated. Though Biden officials see the recent decision as a win, CDC director Rochelle Walensky points out that fully vaccinated Americans are still well-protected against the worst effects of Covid-19.

Coronavirus vaccines “are all highly effective in reducing the risk of severe disease, hospitalization, and death, even in the midst of the widely circulating Delta variant,” Walensky said yesterday.