The Pfizer-BioNTech COVID-19 vaccine is safe and 100% effective in children as young as 12, its manufacturers have said.

The two firms have carried out vaccine trials in the US on 12 to 15-year-olds, which they say were successful.

A spokesperson said they will ask the US regulator to approve emergency authorisation of the jab on school pupils next week and hope to roll it out when the new academic year starts in the autumn.

Currently, Pfizer jabs are only rolled out to over-16s in the US.

Experts believe vaccinating children of all ages will be critical to stopping the pandemic – and helping schools return to normal after months of disruption.

In a study of 2,260 US volunteers, preliminary data showed there were no cases of COVID-19 among fully vaccinated adolescents compared to 18 among those given a placebo.

In the small study that has not yet been published, researchers reported high levels of virus-fighting antibodies which were also found to be higher than in studies of young adults.

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Children had side effects similar to young adults – mainly pain, fever, chills and fatigue, particularly after the second dose.

The study will continue to track participants for two years for more information about long-term protection and safety.

The manufacturers plan to ask the US Food and Drug Administration and European regulators to allow emergency use of the vaccine starting at the age of 12.

“We share the urgency to expand the use of our vaccine,” Pfizer chief executive Albert Bourla said in a statement.

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.

But in a sign that the findings were promising, both manufacturers have already been given permission to start US studies in children aged 11 and younger, working their way to as young as six months.