Federal regulators are expected to authorize the so-called "mixing and matching" of COVID-19 booster shots this week in an effort to provide flexibility for those seeking to maintain protection against the deadly virus.
The news was first reported Monday by the New York Times.
The upcoming announcement by the Food and Drug Administration (FDA) is likely to come along with authorization for boosters of the Moderna and Johnson & Johnson shots and follows the authorization of a third dose for the Pfizer vaccine for many Americans last month.
According to a federal health official familiar with the matter, the FDA was expected to say that, especially for the mRNA vaccines from Pfizer and Moderna that have proved most effective against the virus, maintaining consistency in the vaccine course was still preferable. The agency was still finalizing guidance for the single-shot J&J vaccine.
The Times reports that the government is not expected to recommend one vaccine over another, but could say that it is preferable to stick with the same vaccine for a booster, if possible.
Last week, researchers presented the findings of a federally funded study on mixing and matching to an FDA advisory panel. While the study has not yet been peer reviewed, it suggested that the process is safe and effective. Additionally, for those who were initially vaccinated with the single-shot Johnson & Johnson jab, the study found that a booster of one of the two mRNA vaccines (Pfizer-BioNTech or Moderna) increased protection substantially. While a booster dose of Johnson & Johnson provided a four-fold increase in antibodies, a booster of Pfizer saw a 35-fold increase in antibodies – and a Moderna booster raised antibodies by a factor of 76.
Allowing mixing and matching could alleviate supply issues, make the task of getting a booster simpler for Americans and allow people who may have had adverse reactions to the initial dose to try a different shot.
The move will come after the U.S. said it would recognize mixing and matching of vaccines administered overseas, as was common in Canada and some European countries in the early months of the vaccination campaign, for the purposes of entering the U.S.
Dr. Anthony Fauci, President Joe Biden's chief medical adviser and director of the National Institute of Allergy and Infectious Diseases (NIAID), was bullish on the possibility of mixing and matching boosters on Sunday talk shows.
During an apperance on ABC's "This Week," Dr. Fauci acknowledged the data presented to the FDA panel, adding: "If you boost people who have originally received J&J with either Moderna or Pfizer, the level of antibodies that you induce in them is much higher than if you boost them with the original J&J."
"However, you are talking about laboratory data, which very often are reflective of what you would see clinically," he continued. "But the data of boosting the J&J first dose with the J&J second dose is based on clinical data. So what's going to happen is that the FDA is going to look at all those data, look at the comparison and make a determination of what they will authorize."
Also on ABC's "This Week," Dr. Fauci said of J&J's vaccine that "very likely, this should have been a two-dose vaccine to begin with."
The Associated Press contributed to this report.