Moderna's Covid-19 vaccine appears safe and powerfully effective in teens

Moderna said Tuesday that its Covid-19 vaccine provided strong protection in teens ages 12 to 17 in a late-stage trial.

The finding could pave the way for the shot to become the second authorized in the U.S. for use in teens, after the Food and Drug Administration expanded authorization of Pfizer's shot to include kids ages 12 to 15.

The company said in a press release that the vaccine was 93 percent effective after one dose and 100 percent effective after two doses. The results of its Phase II/III trial,...