FDA authorizes Pfizer and Moderna’s bivalent COVID vaccines

Regulatory NewsRegulatory News | 31 August 2022 |  By 

FDA's Robert Califf and Peter Marks spoke virtually to reporters about authorizing the bivalent vaccine boosters.

The US Food and Drug Administration (FDA) on Wednesday authorized bivalent COVID-19 vaccines targeting the Omicron BA.4/5 subvariants developed by Pfizer-BioNTech and Moderna, asserting that the vaccines, which target the current circulating variant, will be a better match against future mutations of the SARS-CoV-2 virus.
Moderna’s updated booster will be available to individuals 18 and older, while Pfizer’s is authorized for use in individuals as young as 12 years of age. Both shots are authorized for use as a single dose booster to be given at least two months after an individual received their last booster or primary series shot.
With the authorization of the bivalent boosters, FDA said that the monovalent boosters that were previously available are no longer authorized for the age groups eligible for the bivalent boosters, noting that the monovalent primary series that are authorized or approved will remain available for those who have not yet received them.
"We want to make sure that adults and the adolescents covered by this authorization are able to get the most up-to-date version of a booster vaccine and that's why we are no longer authorizing the monovalent – the original booster – for administration to those populations, despite the fact that that original vaccine will remain what is given for the primary series,” said Peter Marks, director of FDA’s Center for Biologics Evaluation and Research (CBER) during a virtual press conference.
BA.1 or BA.4/5?
FDA recommended inclusion of the BA.4/5 spike protein in modified COVID-19 vaccine boosters following a meeting of its Vaccines and Related Biological Products Advisory Committee (VRBPAC) in June, during which the committee overwhelmingly voted to support the inclusion of an unspecified Omicron component. (RELATED: VRBPAC recommends addition of Omicron-component to future boosters, Regulatory Focus 28 June 2022; FDA calls for inclusion of Omicron BA.4/5 in future boosters, Regulatory Focus 30 June 2022).
The agency’s decision to recommend inclusion of the newer BA.4/5 components stands in contrast with its European counterparts, who have authorized or are reviewing updated boosters targetting the earlier BA.1 subvariant. The UK’s Medicines and Healthcare products Regulatory Agency (MHRA) was the first in the world to authorize Moderna’s BA.1-targetted mRNA COVID-19 vaccine earlier this month. (RELATED: UK MHRA is first to authorize Moderna’s bivalent COVID-19 booster, Regulatory Focus 15 August 2022)
On Monday, Swissmedic also temporarily authorized Moderna’s bivalent BA.1-targetted vaccine, and the European Medicines Agency’s (EMA) Committee for Medicinal Products for Human Use (CHMP) is set to review both Pfizer-BioNTech and Moderna’s applications for their bivalent BA.1-targetted vaccines on Thursday.
By comparison, the newly FDA-authorized bivalent vaccines include parts of the original virus and the newer Omicron BA.4/5 subvariants which are the dominant strains in the US. Public health officials fear there will be another spike in new infections this fall and winter.
Marks told Focus during the press conference that the agency “very deliberately” selected BA.4/5 for the updated boosters, noting that the BA.1 subvariant is no longer circulating in the US. He added that the BA.5 subvariant accounts for nearly 90% of US cases at the moment, while the BA.4.6 subvariant accounts for another 6%.
“This gives us a variant that is most up-to-date and will most likely look closer to something that may evolve further in the fall,” said Marks. “It's no guarantee, but the idea here is the more up-to-date you are the better chance you have of looking at what may come afterwards.”
Marks also noted that the latest studies suggest that the BA.1 immunogen in the vaccines is not as good at eliciting the right kind of immune response as the BA.4/5 immunogens.
“Those are suggestive studies, they're not definitive, but they suggest ... immune response to BA.4/5 variants was much more robust against a variety of other variants including BA.1, Delta [and] Beta than the response from BA.1,” he added. “That again goes into this totality of evidence that makes us feel comfortable that this was a good choice.”
FDA said the decision to amend the EUAs was based on a “totality of available evidence” that includes clinical data from the monovalent mRNA vaccines and a clinical study of a bivalent BA.1 vaccine. It also evaluated non-clinical data which included animal studies of the BA.4/5 bivalent vaccines.
While this is the first time the decision to authorize a COVID-19 vaccine for use in the US was not based on clinical data specific to the boosters at hand, Marks and FDA Commissioner Robert Califf said they are confident that there was enough aggregated evidence to warrant amending the EUA.
The officials added that the process to authorize the updated vaccines is similar to how the agency approves seasonal influenza vaccines.
“The FDA has extensive experience with evaluating strain changes for influenza vaccines and is confident in the data supporting these latest booster authorizations,” said Califf. “Importantly, the approach we're taking with the updated COVID-19 booster vaccines mirrors how we have historically addressed changes for the influenza vaccine.”
Marks also said that FDA is waiting for the vaccine manufacturers to present data on younger populations, and if the data looks promising, they may decide to expand the availability of the bivalent vaccines to a larger population.
“We're considering this a transitional year where we feel like everyone needs to get this base of immunity that we understand really well because half a billion people in the world have received it and we believe that building on that is important,” said Marks.
On the decision to authorize the bivalent vaccines without waiting for clinical data specific to each vaccine, Califf stressed that speed is of the essence in a rapidly changing pandemic.
"We have to try to be a step ahead because if we wait for all the proof to come in, the wave will have already passed us by and the damage will have been done," said Califf.
"It's remarkable how the messenger RNA technology enabled a rapid turnaround of the vaccine,” he added. “It's fair for people to raise questions, but this really is the best consensus that we have among the experts that this is the best way to go.”


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