A single dose of either Pfizer’s or Moderna’s updated COVID-19 vaccines will be recommended in most cases moving forward, after the Food and Drug Administration on Tuesday updated its authorizations of the shots to simplify the recommended regimens.
Adults or children older than 5 years of age who haven’t yet been vaccinated will now receive just a single dose of those “bivalent” shots, rather than a series of monovalent doses. Similarly, most individuals who previously received a monovalent vaccine can now be boosted with one bivalent dose.
As part of the updated authorization, adults who are 65 years and older can receive a second bivalent shot at least four months after their initial bivalent booster. Immunocompromised individuals are also eligible to receive an additional bivalent shot.
Adults younger than 65 who already received a bivalent dose are not recommend to receive another shot at this time, however.
The changes also mean that the original “monovalent” vaccines Pfizer and Moderna brought to market in 2020 are no longer authorized for emergency use, in favor of the modified versions the companies later developed that target the omicron variant. (Pfizer’s and Moderna’s monovalent vaccines are still approved, however.)
The updates are based on the outcome of an advisory committee meeting in January. Made up of infectious disease experts, the committee voted 21-0 that both initial and booster vaccine doses should have the same composition. Pfizer’s and Moderna’s bivalent shots are tweaked to better protect against the more infectious BA.4/BA.5 strains, as well as the original version of the coronavirus.
“At this stage of the pandemic, data support simplifying the use of the authorized mRNA bivalent COVID-19 vaccines and the agency believes that this approach will help encourage future vaccination,” said Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, in a statement. “Evidence is now available that most of the U.S. population 5 years of age and older has antibodies to SARS-CoV-2, the virus that causes COVID-19, either from vaccination or infection that can serve as a foundation for the protection provided by the bivalent vaccines.”
Children aged 6 months through 5 years who have had monovalent vaccines may be eligible to receive a bivalent shot depending on their vaccination history. Unvaccinated children in that age range are eligible to receive two doses of Moderna’s bivalent shot or three doses of Pfizer’s, while those who are 5 years old can receive either two doses from Moderna or a single dose from Pfizer.
The FDA said it used immune response data and observational data from England to support its move to a single-dose regimen in most cases.
The agency is expected to hold a meeting in June with the same advisory committee that met in January to discuss the appropriate vaccine strain composition ahead of the fall season. The agency is hoping to build a process for updating COVID shots similar to that used for influenza, to better protect against emerging variants that may evade vaccination.
A Centers for Disease Control and Prevention panel is set to meet Wednesday and will discuss the updates from the FDA as part of a process to formalize vaccine recommendations.
Editor’s note: This story has been updated to clarify that Pfizer’s and Moderna’s monovalent vaccines are still approved, although the FDA is no longer authorizing them for emergency use.