Europe's medicines watchdog said Monday it had begun evaluating the use of Pfizer BioNTech's Covid-19 vaccine for 12- to 15-year-olds, after a similar request in the United States.

Its possible authorisation for children is seen as a crucial step towards achieving herd immunity.

The European Medicines Agency's human medicines committee "will carry out an accelerated assessment of data submitted by the company that markets Comirnaty," said an EMA statement -- referring to vaccine's brand name.

This included results from a large ongoing clinical study involving adolescents from 12 years of age, the Amsterdam-based agency said. 

The agency would announce its findings in June "unless supplementary information is needed", the statement added.

Pfizer and BioNTech on Friday asked the European regulator to authorise their Covid-19 vaccine after filing a similar request with the US authorities earlier in April.

Their vaccine is currently only approved for use on people aged 16 and over.

The move comes after phase 3 trial data showed the vaccine provided "robust antibody responses" and was 100-percent effective in warding off the disease among those aged 12 to 15, the companies said.

If approved, the green light would apply to all 27 European Union member states.

Pfizer and BioNTech added they also planned to seek clearance from "other regulatory authorities worldwide".

No coronavirus vaccines are currently authorised for use on children.

While children and teenagers are less likely to develop severe Covid, they make up a large part of the population and inoculating them -- to prevent them infecting others -- is considered key to ending the pandemic.

Getting older children vaccinated before the next school year begins would also ease the strain on parents juggling the demands of homeschooling and work.

"It's very important to enable children (to make) a return to their normal school lives and allow them to meet with family and friends," Ugur Sahin, co-founder and CEO Germany's BioNTech told German weekly Der Spiegel last week.

BioNTech and Pfizer are also racing to get their jab approved for younger kids, from six months upwards.

The BioNTech/Pfizer shot, based on mRNA technology, was the first Covid-19 jab to be approved in the West late last year.