(NBC) -- Johnson & Johnson has started testing its coronavirus vaccine in adolescents.
The company says it has expanded its phase 2-A trial, which began last September, to now include teens between 12 and 17.
The study will evaluate the vaccine's safety at different dose levels in both a single-dose and two-dose regimens.
It will also evaluate potential vaccination schedules at one, two and three month intervals between doses.
The trial is currently enrolling participants in the United Kingdom and Spain, but will soon expend to teens in the U.S., the Netherlands and Canada.
The vaccine is currently authorized for emergency use in the U.S. as a single dose in adults ages 18 and older.