Pfizer and BioNTech says a trial has shown their COVID-19 vaccine is safe for children aged 5-11.
The firms conducted a trial using a significantly lower dose than that given to adults, with two doses administered 21 days apart.
They say the trial showed the antibody responses in the children were comparable to those recorded in trials among 16-25 year olds.
Pfizer says it will now be admitting the findings to European and US regulators "as soon as possible".
Pfizer CEO Albert Bourla said: “Over the past nine months, hundreds of millions of people ages 12 and older from around the world have received our COVID-19 vaccine.
"We are eager to extend the protection afforded by the vaccine to this younger population, subject to regulatory authorization, especially as we track the spread of the Delta variant and the substantial threat it poses to children,
"These trial results provide a strong foundation for seeking authorization of our vaccine for children 5 to 11 years old, and we plan to submit them to the FDA and other regulators with urgency.”
The two firms say data around vaccination in children under five is expected "as soon as later this year".
Regulators would need to give the green light before any rollout of vaccines to younger children could take place.
However, some medics and experts are against immunising young children because COVID-19 rarely poses a serious risk to them.
Currently, the Pfizer vaccine is approved for use in 12-15 year olds in Ireland, although only with a parent or guardian's consent.