A day after voting in support of Moderna booster shots for certain at-risk Americans, an independent Food and Drug Administration advisory panel on Friday voted to move forward with Johnson & Johnson Covid-19 vaccine boosters.
The panel's decision on J&J was broader then it was for Moderna and Pfizer as it applies to all J&J recipients 18 and older. The timing is also different: It can be administered two months after the initial shot.
For the two mRNA vaccines, the panel agreed they should be authorized for a narrower group: seniors and everyone 18 or older if they have underlying conditions or could be exposed to the virus at work. They also agreed on a timeline of six months after the second shot.
The FDA has not found an increase in concerning side effects from any of the three vaccines' booster doses.
MORE: Why you shouldn't rush to get a COVID-19 vaccine booster shot before it's your turn
The conversation around boosters focuses on whether Americans vaccinated over six months ago need a boost of protection against breakthrough infections in the face of the more transmissible delta variant, though all of the three vaccines authorized in the U.S. are still proving effective against hospitalization and death.
Experts on the FDA panel were quick to highlight that success, emphasizing that the conversation around boosters should not overshadow the vital campaign to get the 66 million unvaccinated Americans vaccinated.
"The people who are in the ICU aren't there because they haven't gotten the third dose, they're there because they haven't gotten any dose," Dr. Paul Offit, an FDA advisory panel member and director of the Vaccine Education Center at Children's Hospital of Philadelphia, said in Thursday's meeting.
Another pertinent debate that the FDA panel will take on Friday is the potential benefits of mixing and matching vaccines for booster shots. Many J&J recipients who feel the single-shot vaccine didn't perform as well as the mRNA vaccines have been clamoring for data on their options for switching.
Early results from a highly anticipated National Institutes of Health study found that boosting with a shot different from what people got the first time appears to be safe and effective.
The non-peer reviewed study evaluated all three vaccines -- Pfizer, Moderna and J&J -- and found that no matter the booster, all study participants saw a "substantial" uptick in antibody levels after a booster shot.
The study also found that for J&J vaccine recipients, antibody levels were higher if they were boosted with Moderna or Pfizer than with J&J. This could indicate stronger protection in the short term, but experts also point out that antibody levels are not the only part of the immune response.
Though promising, more research is likely needed on mixing and matching.
For now, the process will formally move forward with authorizing additional booster doses of Moderna and Johnson & Johnson shots for those who received the same original vaccine, as was the case with the Pfizer booster authorization.
This week's meetings are the first step in that process for Moderna and J&J.
The FDA is expected to issue an authorization in the coming days, and then an advisory panel for the Centers for Disease Control and Prevention will meet to further discuss recommendations about who should get boosters and when.
MORE: FDA authorizes Pfizer COVID-19 vaccine boosters for people 65 and older, other at-risk groups
That panel has scheduled a meeting for next Wednesday and Thursday to discuss boosters for Moderna and Johnson & Johnson.
Once that happens, CDC Director Rochelle Walensky must sign off, which typically happens within 24 hours of the panel's recommendations. That decision is expected by next Friday at the earliest.
Independent FDA panel votes to authorize booster shots for Johnson & Johnson vaccine originally appeared on abcnews.go.com