Advisers to the Centers for Disease Control and Prevention on Thursday voted unanimously to recommend Moderna’s coronavirus vaccine for children and adolescents aged 6 through 17 years.

Their endorsement was neither a surprise, nor urgently anticipated. The Food and Drug Administration authorized the Moderna vaccine for that age group late last week, and the decisions of the two agencies have rarely been at odds.

The recommendation was one of the last hurdles before a second vaccine option becomes available to a large swath of those younger than 18. The vaccine produced by Pfizer and BioNTech has been available to children 5 through 15 since last year and to Americans 16 and older since late 2020.

Moderna’s vaccine was authorized for adults in December 2020. Last June, the company applied to use its vaccine in adolescents aged 12 to 17 years, who would receive 100 micrograms, the same dose as adults. But while the F.D.A. took roughly a month to sign off on Pfizer’s application for older children, it stalled Moderna’s application.

In an announcement in October, Moderna said the F.D.A. was reviewing reports that suggested its vaccine can cause heart problems in adolescent boys. The company also said it would hold off on applying for authorization for children 6 through 11 until the F.D.A. had made a decision for the older children.

In May, Moderna submitted its application to the F.D.A. for children 6 through 11, who would receive 50 micrograms, or half the adult dose.

In a closely watched two-day meeting last week, advisers to the F.D.A. first endorsed the Moderna vaccine for children 6 through 17 years, and then the use of both the Moderna and the Pfizer vaccines for children as young as 6 months.

In their meeting on Thursday, the committee members were presented with data indicating that the Moderna vaccine has an efficacy against symptomatic infection of about 80 percent in children 6 through 11 years and of about 90 percent in adolescents 12 to 17 years. But that data were all collected before the arrival of the Omicron variant, which has shown some ability to dodge immunity.

“We know that Covid can cause severe disease and death among children and adolescents, including those without underlying medical conditions,” said Dr. Sara Oliver, a C.D.C. scientist who presented some of the data.

“The benefits outweigh the risks for mRNA Covid-19 vaccines in all ages,” Dr. Oliver said.

C.D.C. researchers said the Moderna vaccine is safe overall. It carries a very small risk of transient heart problems in adolescent boys aged 12 to 17, but a similar risk has been observed with the Pfizer vaccine, according to Dr. Tom Shimabukuro, a C.D.C. scientist who presented the data.

Several studies have shown that Covid itself carries a much higher risk of heart problems than either vaccine.

Still, to minimize the risk of heart problems, the C.D.C. now recommends that boys and men between ages 12 and 39 years space their doses apart by eight weeks.

Much of the discussion on Thursday was focused on the potential confusion for providers administering different vaccines, at different doses, for several different age groups.

There is no data on the usefulness of a booster shot of the Moderna vaccine for children and adolescents, and the F.D.A. authorized the vaccine only for primary doses. But those data are likely to be available by the time these children would become eligible for a Moderna booster shot, C.D.C. scientists said.