On June 28, a panel of experts convened by the U.S. Food and Drug Administration (FDA) voted 19 to 2 to change the vaccines used since December 2020 to protect against COVID-19.
The change, which only applies to booster doses for people who have already been vaccinated, includes the inclusion of a strain that targets the Omicron variant, which is now responsible for nearly all infections of COVID-19 in the U.S. and across the world. Whole world. But the committee decided not to decide exactly which Omicron strain; Omicron has produced many different sub-variants, starting with BA.1 and now BA.4 and BA.5, the latter two currently responsible for 50% of the COVID-19 cases in the U.S., Including an Omicron strain in the next booster is similar to how flu viruses are exchanged each year to give people the strongest immunity against whatever version of flu is currently circulating.
The committee’s decision is based on several lines of evidence, including that Omicron differs from the original version of the virus in the currently approved vaccines. The initial COVID-19 va Randell, as the booster doses approved in th U.S., all targeted an earlier virus strain known as D614G, which public health excels at as the ancestral strain.
The vaccines protect against becoming seriously ill with COVID-19, hospitalization, or death from the disease. Still, public health experts have offered compelling evidence that such protection could be even stronger if the next booster injections come. The experts also heard from scientists at the U.S. Centers for Disease Control and Prevention (CDC), who provided data showing that these original vaccines are no longer as effective in protecting people from infection with the Omicron variant and its subvariants against the conventional vaccines. Deformation. Of a new version of the vaccine that specifically targets Omicron.
Why is a new vaccine needed now?
The FDA committee has decided that it is time to update the COVID-19 vaccine and that continuing to boost with the current injection will not provide the lasting protection people need. The experts reviewed data on the dominance of the Omicron variant, which has been circulating in the U.S. since December 2021 and has already spawned several sub-variants, including BA.1, BA.2.12.1, BA.4, and BA.5.
The same FDA committee met in April to discuss the criteria for modifying the COVID-19 vaccine and concluded that it would consider the advice of the World Health Organization’s technical advisory group on the composition of the COVID-19 vaccine (TAG-Co-VAC), which analyzes data on the effectiveness of COVID-19 vaccines and makes recommendations on when to switch vaccines if that effectiveness shows signs of declining, just as a comparable WHO group does each year for the flu vaccine. That group concluded in June that while the currently available vaccines from Moderna and Pfizer-BioNTech continue to protect against severe COVID-19 disease — even if people are infected with Omicron variants — stronger immunity to Omicron could come with a booster dose containing a new Omicron-containing vaccine. Dr. Kanta Subbarao, director of the WHO Collaborating Center for Reference and Research on Influenza, explained to the committee the reasoning behind the group’s advice, noting that adding an Omicron-specific component to the next booster would increase the protection that people could get from immunization. “It doesn’t match what so much” [virus strain] will probably circulate, but more about achieving broader immunity [against the existing variants]’ she told the committee.
Subbarao presented data showing that people vaccinated and then infected with Omicron generated a wider range of antibodies that could neutralize more SARS-CoV-2 variants, including the original strain and Omicron, than people who had not been vaccinated and infected with Omicron. Omicron, which elicited primarily immune responses specific to Omicron alone.
However, the WHO has not recommended switching to an Omicron-specific vaccine to immunize people who have not yet been vaccinated, as no data support whether that immunity would be robust enough.
The FDA committee also considered several other pieces of evidence, including that currently circulating versions of SARS-CoV-2, mostly of the Omicron strain, differ sufficiently from the parent virus targeted by the vaccines and that available vaccines are less effective in protecting against Omicron infections than in protecting against other variants. The committee reviewed data showing that while current vaccines still protect against serious diseases, levels of virus-fighting antibodies in vaccinated people, including those who have been boosted, decline over time.
Considering all available data, the FDA panel concluded that there was enough evidence to justify changing the COVID-19 vaccine booster to address better the Omicron variant currently responsible for nearly all infections.
Which version of Omicron will the next vaccine target?
This question caused division among the invited speakers and the committee members. While WHO’s Subbarao suggested including BA.1 in the next vaccine because of the genetic difference from the original SARS-CoV-2 strain in current vaccines, Dr. Peter Marks of the FDA disagreed, preferring to focus on BA.4 and BA.5. “Current vaccines seem to be the least effective against them,” he said.
Both Moderna and Pfizer-BioNTech have provided data on new vaccines they have developed that contain two strains of SARS-CoV-2: the original and one targeting the first Omicron variant, BA.1, in so-called bivalent vaccines. . This approach is similar to that of the flu shot, which typically targets three different strains of flu.
The companies also developed and studied vaccines that targeted only the BA.1 Omicron variant but found that combining the Omicron and the original strains produced a broader immune response against more than just the Omicron strain.
The committee was not tasked with deciding which version of Omicron should be included in the new booster shot. However, the committee members tended to focus on BA.4 and BA.5 as they are increasingly common in the U.S. regarding the efficacy of BA.4 and BA.5-containing vaccines. The committee members urged the companies to continue studying those versions, which both Moderna and Pfizer-BioNTech are doing.
Will the new vaccine provide better protection against Omicron?
That’s the hope, though there’s still limited real-world data on how much stronger the protection against Omicron will be. The companies tested their bivalent vaccines in the lab for their ability to produce virus-fighting antibodies against Omicron, and the committee extrapolated from those studies that the level of antibodies would be sufficient to protect against infection and disease.
It is not clear whether people vaccinated with the bivalent vaccine targeting BA.1 will produce the same levels of antibodies against the newer Omicron subvariants, including BA.4 and BA.5, as against BA.1. Moderna is studying how the immune response to BA.4 and BA.5 generated by its BA.1 bivalent vaccine compares to that against BA.1. Pfizer-biontech has provided early data from a mouse study. Those data showed that its bivalent vaccine did produce antibodies against the BA.4 and BA.5 strains, albeit at lower levels than against BA.1 or the parent virus strain. Both companies continue to study their new vaccines against the newer Omicron sub-variants that are likely to become more common in the coming months.
Are the vaccines safe?
Some committee members questioned whether the bivalent vaccines, targeting two different SARS-CoV-2 strains, would cause more side effects, including myocarditis, an inflammation of heart tissue mainly affecting adolescent males. In short-term data provided by Moderna and Pfizer-BioNTech and reviewed by the FDA, adverse events and adverse events of the new vaccines, measured approximately one month after vaccination, occurred at similar rates to the initial doses, but longer-term follow-up is required.
Will other new vaccines be coming later this year?
The committee also saw data from Novavax, which makes a COVID-19 vaccine using a different technology than the mRNA platform behind the Moderna and Pfizer-BioNTech vaccines. The FDA is still reviewing the company’s request for emergency use authorization and has not yet decided. But many committee members were impressed by the data from Nova vax’s original vaccine candidate, which targets the original SARS-CoV-2 strain but generated strong immune responses against various variants, including against Omicron. Dr. Glenn Gregory, the company’s president of research and development, argued the data was a good reason to deploy Nova vax’s two-dose vaccine to combat current Omicron cases better. But because that vaccine isn’t authorized and the FDA hasn’t reviewed the data, it’s unclear how valid that evidence is.
When could the new booster doses be avail?
Both Moderna and Pfizer-BioNTech have begun production of bivalent vaccines targeting. Modernaoderna said that if the U.S. government decided to boost with that injection, they could have hundreds of millions of doses available by July or August. To have.
However, if regulators decide on a bivalent vaccine containing BA.4 or BA.5 strains, it would take both companies about three months to make those injections and go through the FDA so that those vaccines wouldn’t be until October or November. Available in the FDA and CDC authorize them.
Be staged. With the FDA’s advisory committee recommending that some version of Omicron be included in the next booster shot, it’s up to the FDA to review the available data or request additional data from the vaccine makers to decide which Omicron strains should be included and when people should do it. The panel’s decision is just the first in a long series of steps — and more studies — needed before anyone gets a new COVID-19 vaccine in the fall. “What I’d like to see is additional data and a better understanding of the clinical significance of the impact on severe outcomes and disease,” said Adam Berger, director of clinical and health care research policy at the National Institutes of Health. “I would like more data on the long-term sustainability of any change in the actual vaccine composition.”
