Moderna is preparing to launch a new phase 2/3 trial in the U.S. to assess its promising coronavirus vaccine in adolescent participants aged 12 to 17, though it’s not yet clear when it will start enrolling volunteers.

The drugmaker has not yet publicly announced the phase 2/3 trial, which plans to eventually enroll approximately 3,000 participants at seven sites, according to the company’s Dec. 2 entry on ClinicalTrials.gov. The study aims to assess the highly effective vaccine’s safety, efficacy and reactogenicity in adolescents.

The company is the second COVID-19 vaccine developer to file for Emergency Use Authorization (EUA) with the FDA. The agency’s vaccine advisory committee will meet to discuss the Moderna vaccine on Dec. 17, and an EUA could be granted soon after if the panel offers a positive recommendation.