Pfizer/BioNTech said on Wednesday that its COVID-19 vaccine was 100 percent effective in kids aged between 12 to 15 in phase three clinical trial testing in the U.S.

"Pfizer Inc. and BioNTech SE today announced that, in a Phase 3 trial in adolescents 12 to 15 years of age with or without prior evidence of SARS-CoV-2 infection, the Pfizer-BioNTech COVID-19 vaccine BNT162b2 demonstrated 100 percent efficacy and robust antibody responses, exceeding those recorded earlier in vaccinated participants aged 16 to 25 years old, and was well tolerated. These are topline results from a pivotal Phase 3 trial in 2,260 adolescents," the company said in a statement on Wednesday.

The drugmaker is planning to submit relevant data to the U.S. FDA for approval of emergency use  in this age group.

"We plan to submit these data to (U.S. regulator) FDA as a proposed amendment to our Emergency Use Authorization 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," said Pfizer chief executive Albert Bourla.

German company BioNTech chief executive Ugur Sahin said the results showing high protection for teens were "very encouraging given the trends we have seen in recent weeks regarding the spread of the B.1.1.7 UK variant."