(CNN) – U.S. Food and Drug Administration vaccine advisers are meeting Thursday and Friday this week to address the next round of questions on booster vaccines for Covid-19 – and they could see the first trickle of data on mix-and-match boosters.
This has been one of the biggest ongoing vaccine questions since three different products hit the United States – is it safe, and even desirable, to mix different types of vaccines?
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This is the last question members of the FDA or VRBPAC Vaccines and Related Biologics Advisory Committee will consider. On Thursday, they will focus on Moderna’s request to add a booster dose to her two-dose vaccination schedule. On Friday, they’ll be reviewing Johnson & Johnson’s boosters demand, and it’s only after deciding on those two issues that they’ll turn to the mix-and-match boosters issue.
“What I can say is that, so far, the results suggest that this is something that is safe to do,” Dr Angela Branche, assistant professor at the University of Rochester School of Medicine who helps run some of the clinical trials mixing booster doses, CNN said.
The National Institutes of Health, which is sponsoring the trials, are collecting the data for publication in a peer-reviewed journal and for presentation to VRBPAC on Friday afternoon.
Researchers have tried various combinations. “We started by looking at people who have already received Johnson & Johnson, Moderna and Pfizer and strengthening them with an extra dose of Moderna vaccine,” she said. The researchers also tried to boost the volunteers with the Pfizer and Johnson & Johnson vaccines.
What is the best boost?
The questions they ask include whether there is a difference in the quality and quantity of the antibodies generated with the recall of a person with a different type of vaccine – and whether the wait for a different length of time is important.
Pfizer last month obtained emergency use authorization for a booster dose of its vaccine for some people who are at least six months away from their first two doses.
Moderna has framed its clearance request to reflect the EUA granted to Pfizer. He is asking for the EUA for a half-dose, but for a booster in people who received their first two doses at least six months ago and who are either 65 years and older, at high risk of severe Covid-19 or those whose exposure at work or in their environment puts them at a high risk of serious complications from the infection.
Moderna has much less data than Pfizer showing that its vaccine’s immunity is waning. In fact, several studies have indicated that Moderna’s vaccine offers somewhat stronger protection than that of Pfizer.
A direct study by the United States Centers for Disease Control and Prevention found that Moderna’s vaccine was slightly more effective than Pfizer’s in real life at keeping people from going to the hospital.
Does immunity decrease with Moderna vaccine?
FDA staff were cautious in documents released ahead of Thursday’s meeting. “Some real-world efficacy studies have suggested a decrease in the effectiveness of the Moderna COVID-19 vaccine over time against symptomatic infection or against the Delta variant, while others have not. Overall, however, the data indicates that the COVID-19 vaccines currently licensed or authorized in the United States still provide protection against severe COVID-19 illness and death in the United States, ”they wrote.
“There are many potentially relevant studies, but the FDA has not independently reviewed or verified the underlying data or their conclusions.”
As with Pfizer’s candidacy, Israeli researchers will explain what is going on there. Israel has conducted extensive studies of declining immunity, although most Israelis have received Pfizer’s vaccine. Dr Sharon Alroy-Preiss, director of public health services at Israel’s Ministry of Health and Ron Milo, professor at Israel’s Weizmann Institute, both of whom supported Pfizer’s recall request, are expected to address the VRBPAC Thursday.
The committee will vote on Moderna’s request and is expected to adjourn at 4:45 p.m. EST on Thursday.
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Johnson & Johnson was less specific in its request for booster doses.
The company said it wanted to leave the details to the FDA.
“Based on recent data, it can be assumed that administration of the booster dose will result in increased protection against symptomatic infections, increased strength and magnitude of immune responses against current variants, and increased magnitude of protection against serious disease in all populations. », Indicates the company in its application.
“The booster dose may also increase the likelihood of protection against future variants of concern. A booster dose is recommended at 6 months or later, depending on the strength of immune responses, although a booster dose may be given as early as 2 months. The need for a booster dose and / or its timing will depend on the local / epidemiological situation and the needs of specific individuals / populations.
The FDA said it didn’t have time to verify J&J’s analysis and would ask the committee to decide whether the company has submitted enough information to recommend boosters at two or six months.
The committee is due to vote Friday at 3:15 p.m. ET on whether to recommend allowing a booster dose of the Johnson & Johnson Janssen vaccine, and if so, for whom and when.
Wait can pay
“In general, the longer you wait, the better the boost,” Dr. Dan Barouch of Harvard Medical School and director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center told CNN. Barouch is due to speak to VRBPAC on Friday.
The committee will meet at 3:30 p.m. Friday to discuss the issue of mix and match boosters – although a vote is not expected on this issue.
Rochester’s Branche said it believes the data may indicate that mixing vaccine types for a booster may offer a benefit.
But Barouch, who has also studied mixed booster doses, said there was not enough data to say yet.
“I think there is a lot of potential for mix and match schemes, but the datasets so far are very small,” he told CNN.
Moderna and Pfizer both use mRNA technology – genetic material called messenger RNAs delivered directly to cells to instruct the body to make small pieces of virus to stimulate an immune response. The Janssen vaccine is a vector vaccine, using another virus called adenovirus that is paralyzed so that it cannot replicate, to carry pieces of the coronavirus to stimulate the response.
These two different delivery methods boost the immune system in slightly different ways, Branche said.
“I think the data will show that the reinforcement is certainly very effective in providing additional and longer protection,” she said.
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