Moderna says the phase 2/3 study involved more than 3,700 adolescents ages 12 to 17.
The company says there were four cases of COVID-19 in the placebo group but there were zero cases in the vaccinated group two weeks following the second dose. That means it was 100% effective.
The company also says they found the vaccine was 93% effective when it looked for milder cases of COVID-19 after the first dose.
Moderna says the vaccine was generally well tolerated and no serious safety concerns were identified.
Moderna says it plans to submit the data to the FDA in early June.