Moderna shares once gained more than 4%

Today Moderna shares once gained more than 4%. 

Modernasaid Tuesday its Covid-19 vaccine was 100% effective in a study of adolescents ages 12 to 17, making it the second shot behindPfizer's to demonstrate high efficacy in younger age groups.

The company said it plans to ask the Food and Drug Administration to expand the emergency use of its Covid vaccine for teens early next month. If approved, it would likely dramatically expand the number of shots available to middle and high school students ahead of the next school year. Pfizer and German partnerBioNTechwere clearedto use their vaccine for 12- to 15-year-olds earlier this month.

"We are encouraged that mRNA-1273 was highly effective at preventing COVID-19 in adolescents," Moderna CEO Stephane Bancel said in a press release. "We remain committed to doing our part to help end the COVID-19 pandemic."

The two-dose vaccine, which is given four weeks apart, is already authorized for adults.

U.S. regulators are expected to grant Moderna's request for use in teens. The approval process could take about a month, just in time for some summer activities and fall classes if Moderna submits the data by early June. Pfizer and BioNTech requested expanded use of their shot in adolescents on April 9, for example, and were authorized by the FDA on May 10.