Pfizer Inc. and BioNTech SE’s COVID-19 vaccine has been cleared for use in younger teens in the U.S., paving the way for the mass vaccination of middle- and high-school students before the start of summer camps and the next school year.

The Food and Drug Administration said in a statement Monday that it had expanded the shot’s original emergency use authorization to include adolescents age 12 to 15.

"It was a relatively straightforward decision,” said Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, at a news conference. The vaccine generated a strong immune response, there were no cases of COVID-19 in the vaccinated group, and there were no signs of any new or worrisome side effects, he said.