FDA Approves Updated COVID-19 Vaccines for XFG Variant

FDA Regulatory Actions and Strain Selection

Initially, the FDA advised vaccine manufacturers in early June 2024 that the updated formulas should utilize a monovalent JN.1 vaccine. However, following the further evolution of SARS-CoV-2 and a rise in COVID-19 cases, the agency updated its guidance to recommend the KP.2 strain if feasible, according to the FDA announcement.

The regulatory approvals cover updated mRNA vaccines manufactured by ModernaTX Inc. and Pfizer Inc. Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, noted that vaccination remains the cornerstone of prevention. These updated vaccines meet the agency’s rigorous, scientific standards for safety, effectiveness, and manufacturing quality, Marks said in the agency’s announcement. He added that given waning population immunity from previous exposure and vaccination, eligible individuals should consider receiving the shot.

Eligibility and Dosage Requirements

The updated mRNA vaccines include Comirnaty and Spikevax, which are approved for individuals 12 years of age and older. Meanwhile, the Moderna COVID-19 Vaccine and the Pfizer-BioNTech COVID-19 Vaccine received emergency use authorization for individuals aged 6 months through 11 years, according to the FDA.

Dosage schedules vary by age and prior vaccination history:

• Unvaccinated children ages 6 months through 4 years: Eligible for three doses of the updated Pfizer-BioNTech vaccine or two doses of the updated Moderna vaccine.
• Previously vaccinated children ages 6 months through 4 years: Eligible to receive one or two doses of either updated vaccine, depending on their prior vaccination history.
• Individuals ages 5 through 11: Eligible to receive a single dose regardless of previous vaccination, administered at least two months after any prior dose if previously vaccinated.
• Individuals 12 and older: Eligible for a single dose of Comirnaty or Spikevax, given at least two months after the last dose of any COVID-19 vaccine.

Additional doses are authorized for certain immunocompromised individuals aged 6 months through 11 years, according to agency fact sheets. Side effects are expected to align with those reported from previous mRNA formulations.