Washington, D.C.—The FDA’s expansion of their Emergency Use Authorization (EUA) to allow the use of bivalent COVID-19 vaccine boosters occurred rapidly, with many potential recipients posing questions about what the boosters are and whether they need them.

The “updated boosters” (as referred to by the FDA) from Moderna and Pfizer-BioNTech are administered as a single shot at least 2 months following primary or booster vaccination. The FDA advised that the vaccines contain two mRNA components of the SARS-CoV-2 virus—one of the original strain of SARS-CoV-2 and the other one having common lineages of the BA.4 and BA.5 Omicron variant of SARS-CoV-2.

Here are answers to some common questions to help pharmacists field any concerns:

Who should get them?
The Moderna COVID-19 vaccine, bivalent, is authorized for use as a single booster dose for adults aged 18 years and older, while the Pfizer-BioNTech COVID-19 vaccine, bivalent, is authorized for use as a single booster dose in those aged 12 years and older.

Why are the updated boosters better than the previous ones? The new products include an mRNA component of the original strain to provide an immune response that is broadly protective against COVID-19. Because they also have an mRNA component in common between the omicron variant BA.4 and BA.5 lineages, they provide better protection against COVID-19 caused by the Omicron variant.

Are the new boosters a good match for strains expected to be circulating later this year? The FDA noted that the BA.4 and BA.5 lineages of the Omicron variant are currently causing most cases of COVID-19 in the United States. They also are predicted to circulate this fall and winter.

Is it possible to just get another dose of one of the original boosters? The FDA advised that, with the EUA of the bivalent vaccines, the monovalent mRNA COVID-19 vaccines are not authorized as booster doses for individuals aged 12 years and older.

How do the new bivalent vaccines work? According to the FDA, the Moderna COVID-19 vaccine, bivalent, and the Pfizer-BioNTech COVID-19 vaccine, bivalent, contain mRNA from the SARS-CoV-2 virus. “The mRNA in these vaccines is a specific piece of genetic material that instructs cells in the body to make the distinctive ‘spike’ protein of the original virus strain and the omicron variant lineages BA.4 and BA.5. The spike proteins of BA.4 and BA.5 are identical,” the agency explained.

The data considered by the FDA was somewhat different than usual because trials of the new vaccines are ongoing. Instead, for each bivalent COVID-19 vaccine, the FDA based its decision on extensive safety and effectiveness data for each of the monovalent mRNA COVID-19 vaccines. The safety and immunogenicity data obtained from a clinical study of a bivalent COVID-19 vaccine is that of contained mRNA from Omicron variant BA.1 lineage, which is similar to each of the vaccines being authorized, and from nonclinical data obtained using a bivalent COVID-19 vaccine that contained mRNA of the original strain and mRNA in common between the BA.4 and BA.5 lineages.

Expanded EUA for other groups is expected to be considered soon.

“The COVID-19 vaccines, including boosters, continue to save countless lives and prevent the most serious outcomes (hospitalization and death) of COVID-19,” stated FDA Commissioner, Robert M. Califf, MD. “As we head into fall and begin to spend more time indoors, we strongly encourage anyone who is eligible to consider receiving a booster dose with a bivalent COVID-19 vaccine to provide better protection against currently circulating variants.”

Peter Marks, MD, PhD, director of the FDA’s Center for Biologics Evaluation and Research, stated that the agency worked closely with the vaccine manufacturers to ensure the development of these updated boosters was done safely and efficiently. “The FDA has extensive experience with strain changes for annual influenza vaccines,” Dr. Marks added. “We are confident in the evidence supporting these authorizations.”

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