WASHINGTON — The Centers for Disease Control and Prevention will decide whether to recommend that people “mix and match” their initial COVID-19 vaccine with booster shots from a different manufacturer in late October, CDC Director Rochelle Walensky said Tuesday.

The National Institutes of Health has been conducting studies on every combination of coronavirus vaccines to test the safety and effectiveness of the pairings.

The CDC currently recommends that people eligible for boosters use the same vaccine they received for their initial doses.

But the new studies may conclude that it is safe, or even preferable, for people to mix and match their first doses of Pfizer, Moderna, or Johnson & Johnson vaccine with another product as their booster shot.

“NIH is running the mix and match studies, and they’re doing all nine combinations — of three of what you got with your first dose, and three of what’s possible with the second dose,” Walensky said in an interview with McClatchy. “Those will be available later in October. And once we see those data, then we will have decisions about who should be getting mixes and matches.”

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Federal agencies have authorized the use of COVID-19 booster shots produced by Pfizer for certain groups that are six months out from their last dose. People who are aged 65 and older are encouraged to get the boosters. Those aged 18 and older who are immunocompromised, and those working in environments that put them at high risk, are allowed to get the additional shots.

“Even those people who are currently eligible, I have sort of said ‘walk, don’t run,'” Walensky said. “This is not something that you need to immediately do tomorrow, because our vaccines are continuing to work very well.”

Last week, Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, told McClatchy that the ability to mix and match vaccine products could expand access to booster shots for some people.

“We have not abandoned that concept, because we realize there will be situations for one reason or another where a person may not have the availability to be boosted with the same product that they were originally vaccinated with,” Fauci said.

At a media briefing with other members of the White House coronavirus response team Tuesday afternoon, Fauci said that data would be available on boosting with Johnson & Johnson doses next week, and that data on boosting with Pfizer would come shortly after that.

“Of course, as with all things we do, they must be submitted to the FDA for regulatory approval, so you don’t want to get ahead of the FDA, but at least that’s where the data are right now,” Fauci said.


The FDA is reviewing data on whether to recommend booster shots of Moderna and is awaiting data on boosters from Johnson & Johnson. Eligibility is expected to expand over time to the entire population, Walensky said.

“There’s urgency to making decisions, because we know the American public is interested,” Walensky said. “But our current vaccines continue to do an extraordinary job in protecting people against severe disease and hospitalization, but also against infection.”

Alongside its vaccine booster program, the Biden administration began a push last month to require COVID-19 vaccinations for most federal workers, and said it would issue federal rules mandating that workplaces with more than 100 employees require vaccinations for their workforce.

The CDC may also review whether to mandate proof of vaccination for domestic airline travelers in November, after it issues new guidance requiring vaccination for international travelers from the European Union, Walensky said.

“I think we’ll see where those policies land in early November for international travel, and then potentially have discussions for domestic travel,” she said.

Outside public health advisers to the Biden administration have been encouraging federal vaccine requirements for domestic air travel in recent weeks.


Former President Barack Obama’s transportation secretary, Ray LaHood, recently endorsed such a program and said it would not be difficult to implement.

Fauci has also come out in support of vaccine requirements for domestic air travel in recent weeks.

Walensky said her most urgent priority is getting more than 70 million Americans to take their first vaccine doses.

“We want to increase the number of people who are vaccinated, decrease the amount of community transmission, truly decrease the amount of disease in the community,” she said.

“At this very moment, we have I think much of the science and many of the tools at our disposal to crush this pandemic — to do what it is we need to do,” Walensky said.

“And right now, our inability to do so is really because of our inability to unify as a nation, to unify as a people, to do the right thing against this virus, which is in fact the common enemy,” she said.