Dr. Anthony Fauci, White House chief medical advisor, said Tuesday that data on the safety and efficacy of combining a primary regimen of Covid vaccines from one manufacturer with boosters from another could be available within the next two weeks.
Though the Centers for Disease Control and Prevention approved Pfizer’s booster for seniors and the medically vulnerable on Friday, only those who received Pfizer’s first two doses are eligible for the third. However, the National Institutes of Health is nearing the end of trials that combined boosters and initial doses from Pfizer, Moderna, and Johnson & Johnson, according to Fauci at a White House Covid briefing.
As with all things we do, they must be submitted to the FDA for their regulatory approval,” Fauci said of the so-called mix-and-match trials. “So you don’t want to get ahead of the FDA, but at least that’s where the data are right now.”
Data on Johnson & Johnson’s mix-and-match study could be ready within a week, while Pfizer’s trial might be completed by mid-October. Moderna’s mix-and-match study data is already available, Fauci added.
Pfizer’s and Moderna’s vaccines employ mRNA technology to combat Covid, while J&J’s uses an adenovirus to bolster the body’s immune response. The ability to mix and match vaccines and boosters could give vaccine recipients greater flexibility in picking a third shot to strengthen the waning immunity of their initial doses.
Fauci’s comments came just days after NIH Director Dr. Francis Collins said the agency was still reviewing the results of combining initial doses and boosters from separate vaccine makers. Collins added that Moderna and J&J were weeks away from the CDC and FDA evaluating their boosters.
The NIH announced the start of its mix-and-match vaccine trials on June 1, which included roughly 150 adults who were vaccinated with Pfizer, Moderna or J&J. The participants were boosted with a different third dose approximately three to four months after receiving their initial vaccine regimen.