The U.S. is expanding use of Pfizer’s COVID-19 vaccine to children as young as 12. The Food and Drug Administration said Monday the shot is safe and offers strong protection for younger teens based on testing of more than 2,000 U.S. volunteers. Shots could begin soon once a federal vaccine panel issues recommendations for using the vaccine in 12- to 15-year-olds. Vaccinating children of all ages will be critical to a return to normalcy. Most vaccines rolling out worldwide have been authorized for adults. The latest news is welcome for U.S. families struggling to decide what activities are safe to resume when only the youngest family members remain unvaccinated.