In a press release dated August 31st, the U.S. Food and Drug Administration (FDA) issued an emergency use authorization for both Moderna and Pfizer-BioNTech Covid vaccines incorporating both the original SARS-CoV-2 and BA.4 and BA.5 linages. The authorization allows the Moderna vaccine as a booster for individuals 18 years of age and older and the Pfizer product for those 12 years of age and older. The modification to the mRNA vaccine is intended to extend protection against the BA.4 and BA.5 variants of the original SARS-CoV-2 virus now predominating in the U.S. and in many nations.
In comments justifying emergency use approval, FDA Commissioner Dr. Robert M. Califf stated, "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 vaccine to provide better protection against currently circulating variants". He added, "The vaccines including boosters continue to save countless lives and prevent the most serious outcomes including hospitalization and death as a result of COVID".
Dr. Peter Marks, Director of the FDA Center for Biologics Evaluation and Research stated, "The FDA has been planning for the possibility that the composition of the COVID vaccines would need to be modified to address circulating variants. We have worked closely with the vaccine manufacturers to ensure the development of these updated boosters was done safely and efficiently". He added, "The public can be assured that a great deal of care has been taken by the FDA to ensure that these bivalent COVID vaccines meet our rigor of safety, effectiveness and manufacturing quality standards for emergency use authorization".
The authorization was based on a review of immune response data from 600 adults over 55 years of age previously immunized with a two-dose primary series followed by one booster dose. Protection was compared with volunteers receiving a second booster dose of either the bivalent vaccine with the controls receiving a monovalent vaccine. There was no difference in the manufacturing process for either the monovalent or bivalent vaccines. No differences were observed in clinical response or adverse reaction including the risk of myocarditis and pericarditis.
On Thursday, September 1st the Centers for Disease Control and Prevention issued use recommendations for the bivalent vaccines that are now being distributed.