The Food and Drug Administration is expected to allow giving COVID-19 vaccine boosters that are a different vaccine type from the one used in the initial doses, two sources familiar with the matter said.
The sources confirmed reporting by The New York Times, which on Monday reported that the FDA was planning the move.
The approach is sometimes called “mix and match.” A National Institutes of Health study found the approach to be safe and effective.
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The sources told NBC News on Tuesday that an announcement could come as soon as Wednesday.
State health officials have been asking for this flexibility since late September when the FDA authorized the Pfizer-BioNTech booster, to be given at least six months after the initial series.
An FDA advisory panel voted last week to recommend emergency use authorization for Johnson & Johnson and Moderna booster shots.
Providing mix and match will facilitate vaccine clinics at places like nursing homes. Instead of requiring vaccine providers to bring doses from all three companies, providers can bring what they have in stock, according to the Association of State and Territorial Health Officials.
One source said the process needs to move forward with urgency to give doctors flexibility, and also because some people have already started getting boosters that are different from their initial round of vaccinations.
The Times reported that the government would not recommend one type over another, and could still say that it is preferable to keep the booster the same as the first vaccinations.
Allowing people who got the Johnson & Johnson vaccine to get a Pfizer or Moderna booster means the demand for the J&J vaccine could decline even more, and existing doses on states’ shelves could end up going to waste, according to state health officials.
The NIH study about mixing and matching vaccine boosters found that people who received the Johnson & Johnson vaccine produced stronger antibody levels after they got booster shots made by Moderna or Pfizer, compared to boosters from Johnson & Johnson.
People who were originally vaccinated with the Pfizer or Moderna vaccines and received either company’s booster shot produced similarly strong immune responses, the researchers found.
Dr. Ashish Jha, dean of the Brown University School of Public Health, told TODAY on Tuesday that reports the FDA could allow a mix-and-match approach was good news.
“Clinically, all the data says that mixing and matching is just fine, there’s no downside,” Jha said. He also said it could help in logistics, because people wouldn’t have to stick to the same type of shot.
Of the people fully vaccinated against COVID-19 in the United States, more than 104 million people got the Pfizer vaccine, according to the Centers for Disease Control and Prevention.
More than 69 million people got the Moderna vaccine, and more than 15 million got the Johnson & Johnson vaccine, according to the CDC.
This story first appeared on NBCNews.com.