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Biotechnology company Moderna announced Tuesday that its two-shot coronavirus vaccine produced the same protective immune response in teens as it does in adults, and the firm said it plans to submit the data to U.S. regulators for review in early June.

If authorized, the vaccine would become the second available for adolescents as young as 12. Pfizer-BioNTech's vaccine, which was initially authorized for people 16 and older, was cleared for emergency use in children as young as 12 this month by the Food and Drug Administration.

A gulf has opened between what vaccinated and unvaccinated people can do safely without masks, and many families and pediatricians have been eager to inoculate children and introduce new opportunities for a normal life. If the Moderna vaccine is authorized, it will add a second option for families but may also sharpen questions about vaccine hesitancy and uptake.

The American Academy of Pediatrics has recommended that children get an authorized vaccine once they are eligible. Centers for Disease Control and Prevention data shows that about 4.8 million children between ages 12 and 17 have received at least one shot.

"Parents, reasonably, for this past year have lamented the fact that their children didn't get to go to school, didn't get to play, suffered psychologically and emotionally because of that isolation," said Paul Offit, director of the Vaccine Education Center at Children's Hospital of Philadelphia. "Now, they have this get-out-of-jail-free card. They can send their kids to school and know they're protected . . . and yet, immunization rates in the 12-to-15-year-olds are very low."

Younger people are at far lower risk of severe consequences from infection than older adults, but vaccines for children are seen as essential for building immunity in the community to help end the pandemic. Although severe illness is rare, children can get sick and die or suffer an inflammatory syndrome after infection.

In Moderna's clinical trial, 3,732 adolescents, ages 12 to 17, received two shots of the vaccine or a placebo. Researchers used blood tests to measure the immune response triggered by the vaccine. They found antibody levels equivalent to those of adults who were protected against illness. Instead of waiting for participants to get sick, the trial was designed as an immune bridging trial, to test whether the vaccine triggered responses similar to those in adults. The technique is commonly used to extend the use of vaccines into groups not included in initial clinical trials.

Four children became sick with COVID-19, using criteria employed in the adult trial to identify people with the illness caused by the virus. All the cases were in the group that received the placebo, suggesting the vaccine was protecting the teens. When researchers used a looser definition for COVID-19, which included only a single symptom and a positive nasal swab test, the vaccine was 93% effective after the first dose.

The vaccine had tolerable side effects, including sore arms, headaches, fatigue, chills and muscle aches. The data has not yet been peer-reviewed or published in a medical journal.

Trials in younger children are ongoing for the Moderna and Pfizer-BioNTech shots but are expected to take longer because researchers must ascertain a safe and effective dose, which may differ from what adults receive. Results from the Pfizer trial of children ages 2 to 11 may be available by September or October.

Johnson & Johnson spokesman Jake Sargent said the company is in discussions with regulators to expand testing into pediatric populations. The biotech company Novavax, which is expected to report data from its adult trial soon, has recently expanded testing into 12-to-17-year-olds.

"This really provides us hope for the summer season, for summer camp, for getting back to school in the fall," said Andi Shane, chief of the division of pediatric infectious diseases at the Emory University School of Medicine.