Tens of millions of Americans who received Moderna or Johnson & Johnson’s COVID-19 vaccines will soon hear from the FDA and the CDC on whether they will need an extra booster shot, who is eligible, and whether it’s okay to mix and match vaccines from different brands.
A third booster shot of the Pfizer-BioNTech vaccine was approved last month for people older than 65 and younger people who have a medical condition or work in high-risk environments.
The FDA’s Vaccines and Related Biological Products Advisory Committee is scheduled to meet Thursday and Friday to discuss whether to authorize a third Moderna dose and a second J&J jab.
But scientists on the FDA panel will have limited data to work with. When the group evaluated the third Pfizer shot last month, they were provided with data from Israel, where the vast majority of the population was vaccinated with Pfizer’s original two-shot regime and authorized to receive a third shot over the summer. However, there is no similar nationwide data for either the Moderna or J&J vaccines.
In September, Moderna released data from a small-scale study suggesting that a third shot has the similar effect to Pfizer’s booster in increasing immunity. The study, which followed up on more than 300 participants from an earlier phase 2 trial, found that an extra half dose given six months after the second dose helps boost waning antibody levels. But the results have not been reviewed by independent experts yet.
Both the Moderna and Pfizer-BioNTech vaccines are based on the novel messenger RNA technology. Moderna’s vaccine contains a higher amount of mRNA, the effective ingredient, than Pfizer-BioNTech’s.
As for J&J, the company said last month a second dose given two months after the single shot provided 94 percent protection against moderate-to-severe COVID-19 symptoms. A second dose given six months after the initial shot provided a substantial increase in immune responses.
The FDA advisory panel will also consider the safety and efficacy of combining different vaccines.
A recent study in the U.K. found mixing Oxford–AstraZeneca and Pfizer–BioNTech vaccines to be safe and effective. But the FDA will not take a vote on the matter this week.
If the agency authorizes a booster for either Moderna or J&J, a similar expert group advising the CDC will meet next week to decide should be eligible for the extra shot.
According to the CDC’s vaccination tracker, an estimated 103 million Americans are now fully vaccinated with the Pfizer-BioNTech vaccine, 69 million with Moderna’s and 15 million with J&J’s.