FDA Vaccine Advisory Committee Recommends Booster Vaccines Optimized for Omicron

Today, the Vaccine and Related Biological Products Advisory Committee (VRBPAC) met to discuss and vote on whether to recommend an Omicron component in COVID-19 booster vaccines.

At the end of the meeting, 19 of 21 VRBPAC members voted YES to the following question: “Does the committee recommend inclusion of a SARS-CoV-2 Omicron component for COVID-19 booster vaccines in the United States?”

Since its rise to predominance late December 2021, Omicron and its developing subvariants have been responsible for the vast majority of COVID-19 infections worldwide.

To combat waning immunity, VRBPAC met to discuss whether subsequent COVID-19 vaccine boosters should be formulated with the Omicron variant. VRBPAC is the advisory committee to the US Food and Drug Administration (FDA).

Today’s circulating SARS-CoV-2 viruses are antigenically distinct from those early in the pandemic; the COVID-19 vaccines currently approved under Emergency Use Authorization (EUA) are based on these earliest, no longer circulating strains.

COVID-19 vaccines wane naturally over time, and this decreased efficacy is heightened by Omicron. Though still effective against morbidity and mortality, a primary COVID-19 vaccine series and 1 booster dose may not provide sufficient protection to elderly and other immunocompromised persons.

In an update on the current epidemiology of the COVID-19 pandemic and SARS-CoV-2 variants, US Centers for Disease Control and Prevention (CDC) epidemiology task force representative CDR. Heather Scobie, PhD, MD, emphasized that uptake of a second booster dose has been less than optimal in indicated populations.

Additionally, VRBPAC considered what the strain composition of an Omicron booster vaccine should be. They noted that BA.4 and BA.5 are “squeezing out” the other Omicron subvariants, and combined now account for at least 50% of new COVID-19 infections in the past week.

While presenting the FDA’s assessment of available data for modified COVID-19 vaccine candidates, Jerry Weir, PhD, director of the division of viral products, noted that Omicron has been dominant for over 6 months now. While it is impossible to predict future COVID-19 variants, it is highly likely they will descend from Omicron.

“The available data indicate that an Omicron booster vaccination will increase and broaden the antibody response to SARS-CoV-2 Omicron viruses,” Weir summarized.

The highly infectious Omicron variant has caused unprecedented breakthrough infections in fully vaccinated individuals, as well as a spike in pediatric COVID-19 infections. The rising number of children contracting severe or even fatal COVID-19 led VRBPAC to recommend both the Pfizer-BioNTech and Moderna mRNA COVID-19 vaccines for all Americans 6 months and older.

Before their vote, VRBPAC reviewed all the data presented and considered the following discussion questions:

• Is a change to the current COVID-19 vaccine strain necessary at this time?
• What additional data, if any, would be needed to recommend an updated composition of the primary series vaccine?
• If the booster vaccine composition changes, would continuing use of the prototype primary series vaccine this fall be acceptable?

They discussed the evidence supporting:

1. The selection of a specific Omicron sub-lineage (BA.1 vs BA.4/BA.5)
2. A monovalent (Omicron) or bivalent (prototype + Omicron) vaccine
3. Extrapolating the available clinical data for modified vaccines to different age ranges

After a VRBPAC vote, their recommendation passes to the FDA for authorization, and finally the CDC and director Dr. Rochelle Walensky will decide whether to implement the recommendations.

Thus far, the FDA and CDC have concurred with all of VRBPAC’s COVID-19 vaccine and booster recommendations.