Moderna, Inc. said on Tuesday that its Covid-19 vaccine was effective in children age 12 to 17 years old in a new study, and is planning to ask health regulators in the United States and other countries early next month to expand the shot's use to this age bracket.

The Cambridge, Massachusetts, company said that the vaccine induced immune responses among children that were comparable to those seen in a study of adults last year, a finding that could clear the way for a second shot for use in adolescents after Pfizer-BioNTech, the Xinhua news agency reported.