A panel of experts voted unanimously to recommend that the Food and Drug Administration authorize a booster dose of the Johnson & Johnson COVID-19 vaccine. US health advisors endorsed the booster vaccine Friday, citing concern that Americans who got the single-dose shot aren't as protected as those given two-dose brands. In a 19-0 vote, the panel recommended that the booster dose come at least two months after initial immunization with one shot of the J&J vaccine. It applies to people 18 years and older. During the meeting, J&J presented data that showed the protection of the single shot remained largely stable over time but that a second dose pushed protection to a higher level. Dr. Peter Marks, director of FDA's Center for Biologics Evaluation and Research, said the morning's presentations by J&J didn't include other relevant information about why a booster might be valuable after the initial immunization. "There are data suggesting the effectiveness of the vaccine is actually less robust than the company's presentation here," he said. Marks then called on Dr. Amanda Cohn, a panelist who is also chief medical officer of the National Center for Immunization and Respiratory Diseases at the Centers for Disease Control and Prevention. She cited a study published by the CDC in September that showed the J&J vaccine had effectiveness of around 68% in keeping people out of the hospital for COVID-19 compared with more than 90% for Moderna's vaccine and about 77% for the Pfizer-BioNTech after about four months. Cohn said the J&J vaccine's protection was substantially lower than the mRNA vaccines made by Moderna and Pfizer — even when waning of their protection is taken into account. J&J told the Food and Drug Administration that an extra dose adds important protection as early as two months after initial vaccination — but that it might work better if people wait until six months later. Unable to settle the best timing, the FDA's advisory panel voted unanimously that the booster should be offered at least two months after people got their earlier shot. "I think this frankly was always a two-dose vaccine," said FDA adviser Dr. Paul Offit of Children's Hospital of Philadelphia. "It would be hard to recommend this as a single-dose vaccine at this point." The FDA isn't bound by the recommendation as it makes a final decision — and adding to the debate's complexity, new research also suggests that J&J recipients might have a stronger immune response if their booster dose is from a competing brand. Preliminary results from an ongoing study of different ways to "mix and match" different shots showed that a booster of any sort revved up people's levels of virus-fighting antibodies — at least for a few weeks. And the most dramatic jump came from giving a Pfizer or Moderna shot after the single-dose J&J vaccination. FDA's advisers didn't vote on whether that should be recommended but told the government to allow flexibility with boosters, saying there were no safety red flags even if it's not yet clear just how much difference, if any, mixing and matching may make in long-term protection. "In the real world all these kind of combinations are already happening so I think it's a matter of some urgency for the FDA to help sort out what is admittedly a complicated and challenging scenario," said Dr. Ofer Levy of Boston Children's Hospital. Last month Pfizer boosters started being offered to seniors and younger adults at high risk from COVID-19 because of poor health, jobs or living conditions — at least six months after their initial vaccination. Thursday, the FDA advisory panel recommended the same approach for half-dose Moderna boosters. "This is really -- with the second dose -- bringing it, I think, on par with those other vaccines in terms of effectiveness," said Dr. Archana Chatterjee of Rosalind Franklin University. The FDA will use its advisers' recommendations to decide whether to authorize boosters for both J&J and Moderna. Next, the Centers for Disease Control and Prevention would rule on who should roll up their sleeves. The J&J vaccine was highly anticipated for its one-and-done formulation. But its rollout earlier this year was hurt by a series of troubles including manufacturing problems and some rare but serious side effects including a blood clot disorder and a neurological reaction called Guillain-Barre syndrome. In both cases, regulators decided the shot's benefits outweighed those risks. — Agencies
