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FDA Authorizes mRNA Bivalent COVID-19 Vaccines as Boosters

This Emergency Use Authorization for the Moderna and Pfizer-BioNTech vaccines brings them both one step closer for people to become eligible for these boosters.


The FDA has authorized the Moderna (mRNA-1273.214) and Pfizer-BioNTech Bivalent COVID-19 Vaccines to be used as booster doses. The updated vaccines include 2 mRNA components of the SARS-CoV-2 virus: one of the original wild type strain of SARS-CoV-2; and the other one in common between the BA.4 and BA.5 lineages of the Omicron variant.

“The COVID-19 vaccines, including boosters, continue to save countless lives and prevent the most serious outcomes (hospitalization and death) of COVID-19,” FDA Commissioner Robert M. Califf, MD, said in a statement.

Public health officials have been working to make the boosters available as the northern hemisphere begins to go into the influenza and respiratory illness season. “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,” Califf said in the same statement.

For each of the bivalent COVID-19 vaccines authorized today, the FDA evaluated immunogenicity and safety data from a clinical study of a booster dose of a bivalent COVID-19 vaccine that contained a component of the original strain of SARS-CoV-2 and a component of omicron lineage BA.1.

The FDA considers such data as relevant and supportive of vaccines containing a component of the omicron variant BA.4 and BA.5 lineages. Furthermore, data pertaining to the safety and effectiveness of the current mRNA COVID-19 vaccines, which have been administered to millions of people, including during the Omicron waves of COVID-19, contributed to the agency’s evaluation.

Moderna Booster
In their submission, Moderna cited their study which they said met all primary endpoints, including superior neutralizing antibody response against Omicron (BA.1) when compared to a 50 µg booster dose of mRNA-1273 in previously uninfected participants, as well as potent neutralizing antibody responses against the Omicron subvariants BA.4 and BA.5 compared to the currently authorized booster (mRNA-1273) regardless of prior infection status or age.

The Moderna clinical study evaluated the safety of a booster dose of the bivalent vaccine (original and Omicron BA.1) included approximately 800 participants 18 years of age and older who had previously received a two dose primary series and one booster dose of the monovalent Moderna COVID-19 vaccine, and then at least 3 months later, received a second booster dose with either the monovalent Moderna COVID-19 vaccine or Moderna’s investigational bivalent COVID-19 vaccine (original and Omicron BA.1). 


Pfizer-BioNTech Booster
In the Pfizer-BioNtech filing, the companies said their Omicron BA.1-adapted bivalent vaccine elicited a superior immune response against the Omicron BA.1 variant compared to the companies’ current COVID-19 vaccine. The Omicron BA.1-adapted bivalent vaccine was well-tolerated with a favorable safety profile.

To evaluate the effectiveness of a single booster dose of the Pfizer-BioNTech COVID-19 vaccine, Bivalent for individuals 12 years of age and older, the FDA analyzed immune response data among approximately 600 adults greater than 55 years of age who had previously received a 2-dose primary series and one booster dose with the monovalent Pfizer-BioNTech COVID-19 vaccine.

These participants received a second booster dose of either the monovalent Pfizer-BioNTech COVID-19 Vaccine or Pfizer-BioNTech’s investigational bivalent COVID-19 vaccine (original and Omicron BA.1) 4.7 to 13.1 months after the first booster dose. After one month, the immune response against BA.1 of the participants who received the bivalent vaccine was better than the immune response of those who had received the monovalent Pfizer-BioNTech COVID-19 vaccine.

Both vaccine boosters are indicated for people who it has been at least two months since their completed primary vaccination or have received the most recent booster dose with any authorized or approved monovalent COVID-19 vaccine.

However, an important distinction is that the Moderna vaccine is authorized for people 18 years and older and the Pfizer vaccine is for people 12 years of age and older.

We are confident in the evidence supporting these authorizations,” Peter Marks, MD, PhD, director of the FDA’s Center for Biologics Evaluation and Research, said in the FDA statement. “The public can be assured that a great deal of care has been taken by the FDA to ensure that these bivalent COVID-19 vaccines meet our rigorous safety, effectiveness and manufacturing quality standards for emergency use authorization.”