Moderna said Tuesday its COVID-19 vaccine strongly protects kids as young as 12, a step that could put the shot on track to become the second option for that age group in the United States.

With global vaccine supplies still tight, much of the world is struggling to vaccinate adults in the quest to end the pandemic. But earlier this month, the U.S. and Canada authorized another vaccine — the shot made by Pfizer and BioNTech — to be used