Key FDA panel recommends 2nd J&J shot — and opens door to mixing and matching vaccines

A key federal advisory committee voted unanimously Friday to recommend emergency authorization of an additional shot for all recipients of Johnson & Johnson’s COVID-19 vaccine at least two months after their initial dose, a sign that 15 million Americans will likely be cleared for a second J&J inoculation as soon as next weekend.

If implemented, the recommendation from the Food and Drug Administration’s expert panel would effectively transform Johnson & Johnson from its original formulation as a “one and done” vaccine into a two-dose series akin to those produced by Pfizer and Moderna, with a similar profile in terms of safety and effectiveness.

“I think this, frankly, was always a two-dose vaccine,” said Dr. Paul Offit, a committee member and infectious disease expert with the Children’s Hospital of Philadelphia. “I think it’s better as a two-dose vaccine. It would be hard to recommend this as a single-dose vaccine at this point.”

Vials of Johnson & Johnson COVID-19 vaccine
Vials of the Johnson & Johnson COVID-19 vaccine. (David Zalubowski/AP)

Previously, the J&J vaccine — which relies on viral-vector technology, unlike its mRNA counterparts from Pfizer and Moderna — showed lower protection from symptomatic infection and serious illness. Data presented Friday by the manufacturer suggested that administering a second dose at two months could boost effectiveness above the 90 percent threshold on both fronts.

The move came a day after the same group unanimously backed emergency authorization of a booster shot for older and more vulnerable recipients of the Moderna vaccine.

On Friday, the FDA panel also discussed — but did not yet vote on — whether recipients of the Johnson & Johnson vaccine should be allowed to boost their immunity with a dose of Moderna or Pfizer. Preliminary data from a federal clinical trial published Wednesday found that a mix-and-match (or “heterologous”) approach could produce an even stronger immune response than a second dose of J&J.

Citing that promising National Institutes of Health study — which showed antibody levels rising 76-fold after a Moderna booster and 35-fold after a Pfizer booster, compared with fourfold after a J&J booster — the FDA experts expressed keen interest in mixing and matching during a discussion period that came immediately after the successful J&J booster vote.

“We have to follow the science,” said Dr. Ofer Levy, director of the Precision Vaccines Program at Boston Children’s Hospital. “We’re still in a pandemic here, and if there is opportunity to provide benefit, that’s our job.” Levy went on to note that mix-and-match booster combinations are already happening as “many Americans [take] matters into their own hands.”

As a result, it’s “a matter of some urgency for FDA to sort out what is admittedly a complicated and challenging scenario,” Levy concluded. “We can’t hide from this.”

For now, however, mixing and matching will remain officially off limits. In the next few days, acting FDA Commissioner Janet Woodcock will deliver the agency’s final determination on whether to authorize the boosters. At the end of next week, the Centers for Disease Control and Prevention will engage in a similar process to review the FDA’s decision and issue its own guidance, which state health departments almost always follow.

Sean Edwards, 55, of Bridgton, receives a J&J vaccine from retired physician Nat James during a clinic  in Portland, OR. (Derek Davis/Portland Press Herald via Getty Images)
Sean Edwards of Bridgton, Maine, receives a J&J vaccine from retired physician Nat James. (Derek Davis/Portland Press Herald via Getty Images)

If officials eventually conclude that the science supports a mix-and-match approach, they would likely have to reconvene and revise various emergency use authorizations (EUAs) to allow Johnson & Johnson recipients to receive a Pfizer or Moderna booster. The FDA’s highest-ranking vaccine regulator, Peter Marks, left the door open Friday to future changes.

“Is it possible that there might be an EUA down the road, not right away, on the whole mix-and-match strategy?” asked Dr. Arnold Monto, the panel’s acting chair.

“I would say it’s possible,” Marks replied.

“That’s all I wanted to hear,” Monto said.

Friday’s meeting was intended to address a series of complex questions surrounding a second shot of the Johnson & Johnson vaccine: whether it increases the existing yet exceedingly rare risk of clotting in younger women (early data suggests it does not); whether viral-vector vaccines are “waning” as much as their mRNA counterparts (early data suggests they aren’t); and whether to approve boosters at two months and/or six months (J&J included both timelines in its application).

But ultimately the panel simplified its decision. Noting that one J&J shot has provided less protection against infection, illness and hospitalization from the beginning — and recognizing that the most robust available data found improved protection with a second dose at two months — they voted 19-0 to recommend an additional J&J shot anytime after that point.

“If the vaccine isn’t adequate, it should be boosted in everybody,” explained Dr. Eric Rubin, an adjunct professor of immunology and infectious diseases at the Harvard T.H. Chan School of Public Health.

After that vote, and after a presentation on the NIH’s mix-and-match data, the panel continued to signal a new openness to broadening the U.S. booster campaign in the coming weeks.

“If somebody who has received the [J&J] vaccine would like to get — based on some of these data — an mRNA booster, how is that going to be done?” Monto asked.

Marks, the top FDA regulator, responded by asking the panel what additional information they would require before recommending heterologous boosting — and most panelists seemed to have already made up their minds.

“This is proof of concept,” said Dr. Archana Chatterjee, dean of the Chicago Medical School. “A heterologous boost does work, and in some cases works better than boosting with the same vaccine.”

“I’m sold,” said Dr. Mark Sawyer, an infectious disease specialist at Rady Children's Hospital and a professor of clinical pediatrics at the University of California, San Diego. “We need flexibility and approved access for everybody. … The sooner we let this happen in the most straightforward way, the better off we are.”

The main objection to a mix-and-match approach was the possibility of confusing the public. Yet others countered that medical benefits should trump messaging issues.

The panel concluded the meeting by resolving to consider lowering the mRNA booster age cutoff for otherwise lower-risk Americans from 65 to 40 in the near future, with Monto, the chair, describing himself as a “very strong advocate of doing something that’s understandable and age-based” in order to avoid further confusion.

“This is a dynamic pandemic; we don’t know what the winter will bring,” Levy concluded. “So I think we need to keep an open mind. … I’m generally supportive of coming down in age on the booster, and I look forward to those conversations.”

This post has been updated to include more from the committee's discussion.

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