FDA advisors say new COVID-19 vaccines should be monovalent, targeting XBB
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Key takeaways:
- The VRBPAC voted unanimously to recommend that future COVID-19 vaccines be monovalent.
- The vote was based on data showing that bivalent vaccines are less effective against currently circulating variants.
An FDA advisory committee voted Thursday to recommend changing the composition of the country’s COVID-19 vaccines to be monovalent XBB-lineage vaccines, removing the wild strain of SARS-CoV-2 from the shots.
“Though we're now at a period during which the number of new COVID-19 cases has declined, notably, we still have SARS-CoV-2 as something that could be a real concern in the future, particularly as we move into the 2023-2024 winter season when we are concerned that we may have another wave of COVID-19 during a time when the virus has further evolved,” Peter Marks, MD, PhD, director of the FDA’s Center for Biologics Evaluation and Research, said during a meeting of the Vaccines and Related Biological Products Advisory Committee (VRBPAC).
“The immunity of the population has waned further, and we move indoors for wintertime,” Marks said. “For this reason, we're gathered today and look forward to a robust discussion of the optimal composition for the 2023-2024 COVID-19 vaccines.”
The VRBPAC in January endorsed a plan to simplify COVID-19 vaccine compositions in the U.S. by making all primary series and booster vaccines bivalent shots that target both the original virus and prevalent omicron subvariants. In April, the FDA pulled the authorizations for monovalent COVID-19 vaccines in the U.S. in favor of making them all bivalent.
But the VRBPAC also committed to meet to discuss updating the vaccine compositions for the fall and winter respiratory season, adopting the method used for seasonal influenza vaccine that identifies the predominant circulating viruses.
Since then, a WHO advisory committee has recommended that countries consider making all their COVID-19 vaccines monovalent, targeting XBB sublineages of the omicron variant.
On Thursday, following a full day of discussions and presentations by WHO, the FDA and vaccine manufacturers, the VRBPAC voted 21-0 in favor of the change to monovalent vaccines.
Evidence in favor of the decision was presented by vaccine manufacturers Moderna, Novavax and Pfizer. The data showed that current bivalent vaccines, which were initially authorized by the FDA in August 2022, are less effective against currently circulating XBB variants, which now account for more than 95% of circulating SARS-CoV-2 viruses in the U.S., than previous strains.
All three manufacturers also found that their updated XBB monovalent formulations elicited stronger neutralizing antibody responses against XBB descendant lineage viruses than the current bivalent vaccines.
“The totality of available evidence suggests that a monovalent XBB-lineage vaccine is warranted for the 2023-2024 vaccination campaign,” Jerry Weir, PhD, director of the FDA’s Division of Viral Products Office of Vaccines Research and Review, said during the meeting.
As part of their discussion after the vote, the committee explored specific XXB lineages that should be included in the 2023-2024 formulas. In general, members agreed that there should be uniformity for which strains are included across manufacturers, as well as that XBB.1.5 should be included in the future vaccines due to existent data from manufacturers showing improved responses and because the companies have already begun to work with this formulation, which could mean earlier availability.
“What you heard from the manufacturers is that the XBB.1.5 looks like it seems to be at the front of the line because of some of what is s available in terms of its manufacturing and its properties,” Marks said.
He said a decision will be made quickly for the composition of vaccines for the upcoming 2023-2024 season and that he anticipates manufacturers will be moving forward with obtaining the data needed to inform FDA actions to have the vaccines evaluated with for availability in the September timeframe.
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FDA. Vaccines and Related Biological Products Advisory Committee June 15, 2023 meeting announcement. https://www.fda.gov/advisory-committees/advisory-committee-calendar/vaccines-and-related-biological-products-advisory-committee-june-15-2023-meeting-announcement. Accessed June. 15, 2023.
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