Advisory Committee Recommends Moderna COVID-19 Booster

The committee voted unanimously to support the booster given at least six months after the second dose in the original vaccine.

The FDA’s Vaccines and Related Biological Products Advisory Committee recommended a booster of Moderna’s COVID-19 vaccine for people over age of 65 who are at high risk and people 18 to 64 with workplace exposure or at high risk. All 19 members of the committee voted to support the booster dose, which will be given at least six months after the second dose in the first series. The booster will be at a dose level that is half of what the two doses are.

“This positive recommendation is supported by data on the 50 µg booster dose of our COVID-19 vaccine, which shows robust antibody responses against the original virus, but also against the Delta variant,” Stéphane Bancel, chief executive officer of Moderna, said in a statement. “We remain committed to staying ahead of the virus and following the evolving epidemiology of SARS-CoV-2.”

In September 2021, Moderna had submitted data to the agency supporting the booster application. The phase 2 study of Moderna’s vaccine was amended to offer a booster dose at the 50 µg dose level to interested participants six months following their second dose (n=344).

Investigators found that a booster dose at the 50 µg dose level boosted neutralizing titers significantly above the phase 3 benchmark across age groups, notably in those who were 65 years of age and above. The safety profile following dose 3 was similar to that observed previously for dose 2.

In documents released ahead of the advisory committee meeting, the company gave its rationale for the booster dose being half of the original vaccine. As part of initial

dose ranging study, both 50 and 100 µg were evaluated. Both doses induced at least a 66-fold rise from pre-dose 1 antibody titers. Lower doses of antigen have been shown to be safe and immunogenic for other booster vaccines, such as diphtheria.

Additionally, the company indicated that reducing the booster dose to 50 µg would result in an increase in the worldwide vaccine supply. Moderna plans to have up to 1 billion extra doses available for distribution in 2022.

Safety of the booster was similar to dose 2 of the initial vaccine regimen.

Separately, on August 13, the FDA approved an update to the emergency use authorization for the Moderna COVID-19 vaccine to include a third dose at the 100 µg dose level for immunocompromised individuals 18 years of age or older in the United States who have undergone solid organ transplantation, or who are diagnosed with conditions that are considered to have an equivalent level of immunocompromise.