LONDON — The pharmaceutical developer Novavax says it has asked the European Medicines Agency to extend the authorization of its coronavirus vaccine to children aged 12 to 17 amid a surge of disease across the continent.

In a statement on Thursday, Novavax said its request is based on data from research in more than 2,200 adolescents aged 12 to 17 in the U.S., which found its vaccine to be about 80% effective against COVID-19. The study was done when the delta variant was the predominant virus in the U.S. The main side effects reported were pain at the injection site, headache and tiredness.

The EU drug regulator gave Novavax’s two-dose COVID-19 vaccine for adults the green light in December; the shot has also been cleared by Indonesia, Australia and the World Health Organization, among others. The EMA has previously OK’ed vaccines made by Pfizer-BioNTech and Moderna for use in children from age 6.

The Novavax vaccine relies on an older technology that’s been used for years to make shots for diseases like influenza and pertussis. The Maryland-based Novavax drugmaker uses genetic engineering to grow harmless copies of the coronavirus spike protein in insect cells. Scientists then extract and purify the protein and then mix in an immune-boosting chemical.

Novavax has run into repeated production problems and mainly relies on other factories to make its vaccine. It has delayed delivery of its shots to numerous countries in Europe and despite pledges to make 250 million doses available to COVAX, not a single vaccine has been shared with the U.N.-backed effort to distribute shots to poorer countries.

According to the European Centre for Disease Prevention and Control, more than half of adolescents in the EU have not yet been fully vaccinated against COVID-19. Numerous countries across the continent have recently seen a jump in coronavirus cases, due largely to the spread of the hugely infectious omicron subvariant BA.2 and the relaxation of nearly all COVID-19 protocols.