Pfizer and Moderna have formally asked U.S. regulators to grant emergency authorization for new COVID-19 vaccine boosters for children as young as five.
Pfizer and its partner BioNTech submitted a request to the U.S. Food and Drug Administration (FDA) on Sept. 26, several days after Moderna submitted a request to the FDA.
BA.5 is the dominant strain in the United States at present.
No human data are available for the updated boosters, including for children.
Pfizer is asking the FDA to authorize the updated vaccine for children aged 5 to 11. Pfizer's shot is already available to Americans 12 and older.
Moderna is asking the FDA to authorize the updated booster for children aged 6 to 17. Moderna's booster is available to American adults.
An FDA spokeswoman did not respond to a request for comment.
Request for Babies, Toddlers ComingChildren under five were the last age group to be allowed to receive a COVID-19 vaccine. The FDA authorized the primary series Pfizer and Moderna vaccines for children as young as six months of age in June.
At the time, the companies and health officials said boosters would likely be needed, pointing to how the vaccines have increasingly waned in protection against infection and severe illness.
Moderna's vaccine for young children is administered in two doses. The Massachusetts-based company said that its application for emergency authorization for a third shot, or a booster, for the age group is expected to be completed later this year.
Pfizer's vaccine for young children comes in three doses since a two-dose regimen proved unable to generate what was deemed as a sufficient level of antibodies in some of the population.
Pfizer said Monday that it has launched a phase 1/2/3 study to evaluate the safety and efficacy of the updated booster for children aged 6 months to 11 years. It was not clear when the trial data would be ready.
The companies have said they expect the first human data on the updated boosters to be available by the end of the year.
Submissions for the updated boosters have relied upon human safety and immunogenicity data from a different formulation, a combination Wuhan-BA.1 bivalent. That shot has been cleared in other countries, but U.S. officials decided to ask the companies to replace the BA.1 spike protein with a BA.4/BA.5 one.
The companies also provided data from preclinical experiments done on approximately 18 mice, which they said showed better immune system responses than with the old vaccine.