The Pfizer coronavirus vaccine is "100% effective and well tolerated" in children aged between 12 to 15, according to a new study.
Most Covid-19 vaccines being rolled out worldwide are for adults, who are at higher risk from the coronavirus.
Pfizer's vaccine is currently authorised for people aged 16 and older, but the company is looking to now start vaccinating children.
Pfizer said it now plans to seek approval for use of the vaccine in this age group from regulators around the world and hopes youngsters will start to receive the jab in the US before the next school year.
Researchers examined the use of the Pfizer/BioNTech vaccine in a trial of 2,260 teenagers in the US.
Half were given the jab and the other half were given a placebo drug.
There were no Covid-19 cases seen in the group who received the vaccine and 18 infections among those who did not.
Children had side effects similar to young adults, the company said, mainly pain, fever, chills and fatigue, particularly after the second dose.
Albert Bourla, chief executive of Pfizer, said: "We share the urgency to expand the authorisation of our vaccine to use in younger populations and are encouraged by the clinical trial data from adolescents between the ages of 12 and 15.
"We plan to submit these data to FDA (the US Food and Drug Administration) as a proposed amendment to our emergency use authorisation in the coming weeks and to other regulators around the world, with the hope of starting to vaccinate this age group before the start of the next school year."
Pfizer is not the only company seeking to lower the age limit for its vaccine. Results also are expected soon from a US study of Moderna's vaccine in 12 to 17-year-olds.
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But in a sign that the findings were promising, the FDA has already allowed both companies to begin US studies in children aged 11 and younger, working their way to as young as six months.
AstraZeneca last month began a study of its vaccine among six to 17-year-olds in Britain, Johnson & Johnson is planning its own paediatric studies, and in China, Sinovac recently announced it had submitted preliminary data to Chinese regulators showing its vaccine is safe in children as young as three.
