CHICAGO (NewsNation Now) — The Food and Drug Administration could endorse mixing COVID-19 vaccine brands as early as this week, according to a new report from The New York Times. The Trump administration’s testing chief said it would make sense based on recent data.

“The only question is the studies have been relatively small and is it safe, but everything I’ve seen so far suggests that it’s safe,” Dr. Brett Giroir said on NewsNation’s “The Donlon Report” on Monday. “And mixing that dose is extremely effective and providing additional protection.”

The results of a study endorsed by the National Institutes of Health can be seen below. It has not yet been peer-reviewed, but found mixing vaccines provided strong protection, as did sticking with one brand for the entire course.

American health leaders at first advised against straying from the prescribed dose schedule for each brand when the vaccines were rolled out. But studies have shown mixing the mRNA vaccines made by Moderna and Pfizer doesn’t result in any safety or efficacy concerns.

For Johnson and Johnson vaccine recipients, protection gets even better with one dose of an mRNA vaccine, the studies found.

“I think it’s very clear that if you had J&J, you need a second dose,” Giroir said. “A second dose of J&J is very, very effective. They just presented that data. And it seems to be true that a second dose of Moderna or Pfizer could be even more effective than a second dose of J&J.”

Currently, only Pfizer vaccines have the full authorization of the FDA and Centers for Disease Control and Prevention to be given as a booster dose, and only some Americans are eligible. To get one, you must be 65 or older, or be 18 years or older and have an underlying condition or work or live in a high-risk setting. In addition, only people who’ve had two doses of the Pfizer vaccine already can get a third shot.

Moderna and Johnson and Johnson have submitted booster dose data to the FDA, but it has not given its endorsement yet. That is widely expected, however, after an FDA advisory panel voted to recommend the agency give the green light for both brands.

Giroir said Colin Powell’s death highlights the importance of booster doses for the vulnerable. Powell died Monday after complications from the virus that may have stemmed from his cancer — or possibly even his cancer treatment.

“This is the kind of person who’s at high risk, even though he has been vaccinated, and why these folks need at least three vaccines to get them in the ballpark of protection,” Giroir said.