The booster-shot question that has been on the top of many minds for many months will be addressed today when the Food and Drug Administration’s vaccines advisory committee reconvenes to complete a two-day meeting. The question before it: Should people who got the one-dose Johnson & Johnson vaccine get a booster shot, and if so, when?
Another top-of-mind question, however, may end up not being addressed by the FDA’s Vaccines and Related Biological Products Advisory Committee (VRBPAC). If the highly active discussion on Twitter is any indication, people who got the J&J vaccine want to know if they should be boosted with one of the messenger RNA vaccines from Pfizer-BioNTech or Moderna.
That option doesn’t appear to be on the table for today.
During Thursday’s online meeting to discuss Moderna’s application for a booster shot, the question — actually questions — that will be put to the committee during today’s discussion about the J&J application was temporarily posted by mistake. Nowhere among them was a question about whether J&J vaccine recipients ought to get a heterologous boost, in other words a boost with a different vaccine.
Data will be presented today on a study of mix-and-match boosting conducted by the National Institutes of Health. But according to the meeting schedule, it will be at the end of the day, after VRBPAC votes on the J&J booster application. There’s no provision on the schedule for a vote on heterologous boosting.
People who got the one-and-done J&J vaccine have been in booster-shot limbo as the manufacturers of the mRNA vaccines have argued that an increasing number of breakthrough cases among fully vaccinated Americans and declining antibody levels signal a need for boosters.
If protection from two doses of the mRNA vaccines is already wearing off for people who were vaccinated early in the U.S. rollout, so the thinking goes, surely people who got only one dose of the J&J vaccine are also becoming increasingly vulnerable.
But available data don’t necessarily show a decline in protection from the J&J vaccine — or, for that matter, huge gains from a J&J booster shot. The vaccine’s protection against serious illness was never as high as the protection offered by the mRNA vaccines in the early days after vaccination. But it hasn’t waned either. The vaccine’s efficacy against moderate to severe disease was nearly 73% after one dose, and about 75% after two.
J&J submitted several studies to the FDA, evaluating both a second dose after two or three months and a booster given at least six months after the first dose.
For VRBAC, voting on a J&J booster will come in stages. The committee will first be asked to vote on whether the available evidence supports the safety and effectiveness of giving a dose of the J&J vaccine as a booster for all adults 18 years of age and older at least two months after their first dose.
If the committee votes “Yes” on that question, it will be asked if the data suggest that extending the interval between the first shot and the booster to at least six months might make the booster shot more effective. If the committee votes “No” to the first question, members will be asked if the data support a booster shot given six months or more after the first shot.
The vote places no restrictions — other than being age 18 and older — on who should get a J&J booster if one is approved. But given the vaccine’s safety profile — it has been linked to a small but real risk of serious clotting problems seen mainly in women under the age of 50 — there will likely be discussion about whether a J&J booster for anyone who got the vaccine is warranted.
There might be discussion about this regardless. Both the Pfizer/BioNTech and the Moderna boosters were greenlit for specific groups of people, albeit large groups that include people over 65, people 18 to 64 with medical conditions that increase their risk from Covid, and people who live in or work in places which increase their risk from Covid.
Matthew Herper and I will be live blogging the meeting, which you can watch here, starting at 8:30 a.m. EDT. We will be posting our updates and analysis below in reverse chronological order; check back often.
— Helen Branswell
J&J’s vaccine is different than the mRNA vaccines
9:00 a.m.: The subhead above may seem self-evident. But it’s important to remember as today’s discussions begin that the Johnson & Johnson vaccine (sometimes called the Jannsen vaccine, because that’s the name of J&J’s vaccine division) is made differently than the Pfizer-BioNTech and Moderna vaccines. It is a viral-vectored vaccine: a weakened cold virus has been modified to carry genetic information about the SARS-CoV-2 spike protein.
This vaccine underwhelmed initially, because its efficacy was substantially lower than that of the messenger RNA vaccines. But where the efficacy of those vaccines — at least the Pfizer one — has declined substantially in the first six or eight months after administration, the J&J vaccine’s efficacy hasn’t.
A letter published this morning in the New England Journal of Medicine briefly charts the different ways the three U.S.-authorized vaccines engage with the immune system. The senior author is Dan Barouch, an immunologist at Beth Israel Deaconess Medical Center who led development of the modified adenovirus platform that the J&J vaccine uses.
“The [J&J] vaccine induced lower initial antibody responses, but these responses were relatively stable over the 8-month follow-up period, with minimal-to-no evidence of decline. These findings have important implications for waning vaccine immunity, although correlates of protection from SARS-CoV-2 are not yet defined,” Barouch and colleagues noted.
These features — lower initial efficacy but no evidence yet of decline — may create a dilemma in today’s discussion. There has been concern for some time among VRBPAC members and members of the CDC’s vaccine advisers, the Advisory Committee on Immunization Practices, that people who received the one-dose J&J vaccine should probably get a second shot. The evidence may actually suggest it isn’t urgently needed. But given that boosters for both Pfizer and Moderna were authorized, it seems likely J&J’s booster or second shot will be approved too.
The big question will be around the timing of the second shot — at two months after the first shot, or at 6 months?
— Helen Branswell
A cheat sheet for today’s panel
7:00 a.m. Yesterday’s panel regarding the approval of booster shots for the Moderna vaccine brought some drama but also ended with a unanimous vote backing the boosters. What’s in store for today? Here’s a handy list of questions that may arise.
Should all J&J recipients get a booster?
A second shot of the J&J vaccine has been tested in two studies. One was a study in which 30,000 patients received two shots two months apart. They had fewer cases of moderate or severe Covid-19 than those who received a placebo. The second study showed antibody levels rose after a six-month booster. Unlike Moderna, J&J is asking for authorization for everyone who has received its single-dose vaccine to get another shot.
Was the J&J vaccine always going to be a two-dose vaccine?
In the FDA briefing documents posted Wednesday, the J&J vaccine doesn’t appear to be showing waning efficacy. Instead, the FDA staff said the effectiveness of the single-shot J&J vaccine appears to always have been lower than that of the two-dose mRNA vaccines.
At the time the J&J vaccine was authorized, some members of the VRPAC were already wondering whether a second dose would be needed. Paul Offit, a vaccine researcher from Children’s Hospital of Philadelphia, wondered aloud how to communicate to the public that a second shot might be needed. So one argument for granting J&J’s request for authorizing a booster is that it always seemed as if two doses might be needed.
Should J&J recipients get a J&J booster, or something else?
One of the most anticipated parts of the two-day meeting will come at the end of the day, when the panel will discuss a study by the NIH on mixing and matching booster shots. These data show higher levels of antibodies for those who got the Moderna shot after a J&J shot. But the study is small and has other flaws.
How should we think about safety?
Thursday’s panel about the Moderna vaccine was filled with discussion about one rare side effect: myocarditis. Dozens of cases appear to occur for every million men between the ages of 18 and 24 who receive the vaccine. The J&J vaccine has a different safety profile, but may cause a condition called thrombotic thrombocytopenia, a condition that causes both excessive bleeding and dangerous blood clots. That condition is also rare, occurring in perhaps three people with Covid-19 per million, and in data presented during the spring seemed most common in women in their 30s. The vaccine has also been linked to several cases of Guillain-Barré syndrome.
There was little discussion of this in FDA briefing documents. For every case of either side effect, the CDC has estimated that the vaccine prevented thousands of Covid-19 cases. The panel may discuss how to balance these rare risks in younger people, who are at lower risk from Covid-19, too.
If you’re watching the panel and want to think about the state of medicine, consider this: the Covid-19 vaccines are a tremendous success, based largely on the efforts of pharmaceutical companies. But relying on companies to conduct clinical trials can mean some questions don’t get answered. For instance, what happens if we want to mix and match booster shots? The question of how one could change the system so questions like that get answered is left as an exercise to the reader.
— Matthew Herper
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