WASHINGTON, United States

Novavax said Thursday its COVID vaccine was 82 percent effective among adolescents during the period when the Delta variant was dominant, and the US biotech now plans to submit for regulatory approval in this age group.

The two-dose vaccine, which is based on synthetic proteins that mimic the spikes that dot the surface of the virus, was found to be safe and effective among more than 2,200 adolescents aged 12 through 17 as part of a phase three clinical trial carried out in the US, the company said in a statement.

"We are encouraged by the results in this adolescent population given the ongoing need for alternative vaccine options," said Filip Dubovsky, the company's chief medical officer.

"We believe the Novavax vaccine could be a differentiated option for this younger population given its established protein-based technology already used in other vaccines, and the positive responses demonstrated against variants."

The Pfizer vaccine is currently the only authorized shot for teens, but comes with certain risks, particularly for adolescent males, of heart inflammation.

But these rare concerns only became clear once the vaccine was administered to millions of people, rather than in clinical trials that test only thousands.

Maryland-based Novavax was an early frontrunner in the race to develop a COVID vaccine, but the company was beset by production difficulties that impeded authorization.

It finally submitted a request to US regulators at the end of January to use its vaccine in adults, which has already been approved in the European Union and Britain, leading to its recognition by the World Health Organization.