Pfizer is soon expected to submit data to the US Food and Drug Administration (FDA) regarding safety of its mRNA Covid vaccine for children ages 5 to 11, media reports said.

“It’s a question of days, not weeks,” Pfizer chief executive Albert Bourla said on ABC’s “This Week.”

While the FDA has the authority to approve the vaccines for children, Bourla said Pfizer will be ready to manufacture a vaccine specifically for children.

“It is a different formulation,” he said.

“It’s one-third of the dose that we are giving to the rest of the population.”

Last week, the US drugmaker and its German partner BioNTech, in a study, showed that their mRNA Covid vaccine is safe, well tolerated and produces robust neutralising antibody responses in children aged 5 to 11 years.

The results are based on the first-ever trial of any Covid-19 jabs in kids under 12 years of age, Pfizer said in a statement.

The Phase 2/3 study enrolled 2,268 children who were 5 to 11 years of age and were given a two-dose regimen of 10 microgram 21 days apart. A smaller dose than the 30 microgram dose is used for people 12 and older.

The antibody responses in the participants given 10 microgram doses were comparable to those recorded in a previous Pfizer-BioNTech study in people 16 to 25 years of age immunised with 30 microgram doses.

Further, the Covid-19 vaccine was found to be well tolerated, with side effects generally comparable to those observed in participants 16 to 25 years of age.

While the early pandemic did not affect children much, the recent wave of delta Covid variant has increased paediatric hospitalisations. Children now make up an increased portion of cases in many US states and parents are anxious to get their children vaccinated, especially as schools reopen.

So far, of the vaccines available in the US, only the Pfizer-BioNTech shots have been cleared by the FDA for people as young as 12, while Moderna’s and Johnson & Johnson’s vaccines have been authorised for adults.

Very few countries are vaccinating children younger than 12; Cuba this month started vaccinating children as young as 2 years old with a domestically developed vaccine, and Chile this month said children as young as 6 years old could receive China’s Sinovac vaccine.