The Food and Drug Administration's vaccine advisory panel unanimously voted Friday to recommend authorizing booster shots of Johnson & Johnson's one-dose coronavirus vaccine for people 18 years or older, at least two months after the first dose. The FDA typically follows the panel's advice.
Before the vote, a top agency official, Dr. Peter Marks, said the agency might consider regulatory action that would allow Johnson & Johnson recipients to receive booster shots of Moderna's or Pfizer's vaccines. But Marks, who oversees the FDA's vaccine division, gave no timetable for any decision, saying only that authorization of a different vaccine as a booster for Johnson & Johnson recipients was "possible."
Many panel members said a second dose was important because the first dose did not provide strong enough protection. Unlike the other vaccines available in the United States, Johnson & Johnson chose to seek authorization for a single dose -- a decision that some committee members couched as a mistake in hindsight.
"I think this frankly was always a two-dose vaccine," said Dr. Paul Offit, an infectious-disease expert at the Children's Hospital of Philadelphia.
Last month, Pfizer boosters started being offered to senior citizens and younger adults at high risk from covid-19 because of poor health, jobs or living conditions -- at least six months after their initial vaccinations. On Thursday, the FDA advisory panel recommended the same approach for half-dose Moderna boosters.
Johnson & Johnson representatives presented their case Friday morning during a meeting of the advisory panel, arguing that a second dose given either two months or six months after the first shot increased antibody levels, part of the immune response to vaccines. They also said the single dose remained durable.
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Federal vaccine experts also walked through the company's data, pointing out its shortcomings. They warned that the two-month booster trial followed up with study volunteers only for a short period of time after their second shots. They also noted that a key test used by the company to measure the antibodies produced by a booster had a low sensitivity, calling the results into question -- a concern raised by panel members Friday.
Dr. Archana Chatterjee, an infectious-disease expert at Rosalind Franklin University in Illinois, asked the FDA why it convened the panel if its own experts had not had time to verify the company's data. Marks, who has argued for a "harmonized" approach to the booster policy, said it could have taken a month to verify all of the data from the company's largest-scale two-dose trial and several weeks to review the smaller studies.
The regulators did not see any evidence of serious safety concerns in the booster studies. But they noted that they were not afforded enough time to independently review much of the data that Johnson & Johnson provided in its application for authorization, including in its large, two-dose trial that the company said made a clear case for bumping up protection with boosters.
Some federal officials appeared skeptical of the claims the company made about the efficacy of one dose and expressed worry that those who received it are not as protected as Moderna or Pfizer recipients.
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"It was used as an outreach vaccine," Marks said. "Many of the people who got that may not have been part of a health maintenance organization or an organized health care system."
Dr. Amanda Cohn, a Centers for Disease Control and Prevention official, said "the effectiveness or protection with a single dose of the J&J vaccine is not equivalent" to two doses of the Pfizer or Moderna vaccines.
Some committee members argued that the vaccine should have been used in a two-dose regimen from the start.
Panel members conveyed concern about the size of the study Johnson & Johnson used to ask for authorization of a six-month interval. "I'm not sure why you're asking for an indication that would apply to millions of patients with a data set that includes 17 patients," said Dr. Eric Rubin, an adjunct professor of immunology and infectious diseases at the Harvard T.H. Chan School of Public Health.
After voting on a Johnson & Johnson booster, the panel heard from Dr. Kirsten Lyke of the University of Maryland School of Medicine about a study in which she and her colleagues found that Johnson & Johnson recipients may benefit more from a Moderna or Pfizer booster.
Lyke and her colleagues carried out a "mix-and-match" study with different combinations of the three vaccines.
Preliminary data from the study showed that those who got a Johnson & Johnson shot followed by a Moderna booster saw their antibody levels rise 76-fold within 15 days, whereas those who received a Johnson & Johnson booster saw only a fourfold rise in the same period. A Pfizer booster raised antibody levels in Johnson & Johnson recipients 35-fold.
The government says all three U.S. vaccines continue to offer strong protection against hospitalization and death from covid-19, and that the priority is getting first shots to the 66 million eligible but unvaccinated Americans who are most at risk. But with the spread of the extra-contagious delta variant and signs of waning immunity against milder infections, the nation is moving toward a broader booster campaign.
Several panelists said they felt comfortable with the amount of data the National Institutes of Health researchers had gathered to recommend FDA authorization. Dr. Ofer Levy, director of the Precision Vaccines Program at Harvard's Boston Children's Hospital, said many Americans had already taken the matter into their own hands and urged the FDA to step in.
"It's a matter of some urgency for FDA to help sort out what is admittedly a complicated and challenging scenario," he said. "We can't hide from it. And I do think we need to give guidance to the public."
Cohn, the CDC official, said the FDA could perhaps allow for general language in its authorizations of the vaccines that would allow for combinations. "From a public health perspective, there's a clear need in some situations for individuals to receive a different vaccine," she said, including those who do not have access to the same vaccine they received the first time or those who now realize they might have increased risk of some side effects from the same vaccine.
The National Institutes of Health trial looked only at antibody levels, which on their own are an insufficient measure of how well different combinations would protect people. Lyke said studies on immune cell responses were underway.
SHOTS FOR KIDS
Separately, U.S. health officials are setting the stage for a national covid-19 vaccination campaign for younger children, inviting state officials to order doses before the shots are authorized.
Pfizer's coronavirus vaccine is currently being given to people as young as 12 in the U.S. In the next three weeks, federal officials plan to discuss making smaller-dose versions available to the nation's 28 million children between the ages of 5 and 11.
To help states and cities prepare, the Centers for Disease Control and Prevention this week sent out a seven-page document with guidance on how to set up expanded vaccination programs.
For example, it notes pharmacies in every state can give covid-19 shots to children, but it clarifies that only doses prepared and packaged specifically for children are to be used for those under 12.
It doesn't speak to some thornier questions, however, such as how much school-based clinics should be relied on or whether kids should be required to get shots as a condition of school attendance.
Those questions will have to be worked out in each state and city.
The guidance comes as communities are gearing up for a new phase in the 10-month-old effort to vaccinate as many people as possible against a virus that has killed more than 720,000 people in the U.S.
The disease has been most dangerous to older adults, who have higher rates of death and hospitalizations than children. But some kids are at risk for severe illness, and more than 540 U.S. children have died from covid-19, according to the American Academy of Pediatrics.
Just as important, health officials believe that vaccinating children will reduce virus spread to vulnerable adults.
Pfizer and its German partner BioNTech are furthest along in researching use of their vaccine in younger children. They say a two-dose vaccine series -- one-third as potent as the version given to people over 12 years old -- is safe and effective in 5- to 11-year-olds.
An independent expert panel that advises the FDA is scheduled to publicly debate the evidence at a meeting in late October. If the FDA authorizes the kid-size doses, a different expert panel advising the CDC would take up the matter in early November, and then offer a recommendation to the CDC.
It's not yet clear how many people will get shots for their younger kids right away, said Dr. Marcus Plescia, chief medical officer of the Association of State and Territorial Health Officials.
"We're going to have potentially a very busy, and perhaps modestly chaotic time" initially, he said.
But there probably will not be the kind of heavy demand seen when shots first became available for adults, he added.
The new CDC guidance calls for shots to be given at the offices of pediatricians and family-practice doctors, and at pharmacies, rural health clinics and federally-qualified health centers.
The CDC discussed the option of vaccination clinics at schools, but stopped short of endorsing that as a primary way to get kids vaccinated. School clinics are logistically appealing, but many parents may not be comfortable with the idea, Plescia said.
The guidance also warns health care providers to only use doses that have been prepared especially for kids, and not try to fraction adult doses, Plescia noted.
CDC guidance said immunization program managers can start ordering doses Wednesday, though vials wouldn't be delivered until the FDA and CDC sign off.
Meanwhile, Pfizer said Friday that it has requested to have its coronavirus vaccine licensed for children ages 5-11 across the European Union. If EU regulators agree, it would be the first opportunity for younger children in Europe to get immunized against covid-19.
With much of Europe's adult population already immunized, many countries are seeing increasing outbreaks of the disease in children while schools are mostly open and operating with sometimes patchy guidance on mask-wearing and social distancing.
The World Health Organization has said vaccinating children was not a priority because they are far less likely to develop serious disease or to die of covid-19. The health agency has repeatedly urged rich countries to share their doses with poor countries instead of expanding domestic eligibility so the world's vulnerable populations can be immunized.
Information for this article was contributed by Noah Weiland, Carl Zimmer and Sharon LaFraniere of The New York Times; and by Matthew Perrone, Lauran Neergaard, Mike Stobbe, Lindsey Tanner and staff members of The Associated Press.