The coronavirus vaccine made by Moderna is safe and produces a powerful immune response in children ages 6 through 11, the company said Monday.

One month after immunisation was complete, the children in Moderna’s trial had antibody levels that were 1.5 times higher than those seen in young adults, the company said.

Moderna did not release the full data, nor are the results published in a peer-reviewed journal. The results were announced one day before an advisory committee of the Food and Drug Administration is scheduled to review data for the Pfizer-BioNTech vaccine in children 5 through 11.

Moderna tested two shots of the vaccine given 28 days apart in 4,753 children. They received 50 micrograms of vaccine, half the adult dose, in each shot. (Last week, based on data showing that the half dose is still highly effective, the FDA authorised a booster shot of the Moderna vaccine at this dose.)

Moderna submitted study results for the vaccine’s use for adolescents 12 through 17 in June, but the FDA has not yet announced a decision for that age group.

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Some research indicates that the Moderna vaccine may increase the risk of a rare side effect called myocarditis, an inflammation of the heart muscle, in boys and young men. In July, the FDA asked both Pfizer and Moderna to expand the size of their trials in order to detect less common side effects.

In children aged 6 through 11, most of the side events were mild or moderate; the most common were fatigue, headache, fever and pain at the injection site, Moderna said in its statement Monday. An independent committee will continue to review the vaccine’s safety in the trial participants for 12 months after the second dose.

Moderna is still recruiting children aged 2 through 5 and 6 months to under 2 years for trials of the vaccine in those age groups. The company has enrolled about 5,700 children in the United States and Canada in the trial.

Moderna plans to submit the results soon to the FDA and to regulatory agencies in Europe and elsewhere, the company said.