(CNN) — Moderna’s COVID-19 vaccine is safe and generated an immune response in children aged 6 months to 17 years that is comparable to the response in adults, according to documents released by the US Food and Drug Administration (FDA) ahead of key meetings of its independent advisory group on vaccines.
FDA vaccine advisers will assess next week that Moderna’s COVID-19 vaccines for children ages 6 months to 5 years and ages 6 to 17 years should receive emergency use authorization.
Children under the age of 5, about 18 million people, are the only age group in the United States not yet eligible to receive a Covid-19 vaccine. Moderna’s vaccine is currently available only to people 18 years of age and older. Pfizer’s covid-19 vaccine is already licensed for children 5 years and older. FDA advisers will also evaluate its vaccine for younger children next week.
Background documents released ahead of the FDA committee meetings describe how Moderna’s vaccine was evaluated using immune-bridge studies to see if the immune response among younger people was comparable to that of people ages 18 to 25, who are already eligible to receive the vaccine.
“Immune bridging success criteria were met for all four pediatric age cohorts,” the FDA document stated.
In trials evaluating more than 6,000 children ages 6 months to 6 years, Moderna found that two 25-microgram doses of the vaccine taken 28 days apart produced an immune response similar to a two-dose series of the vaccine given to adolescents From 18 to 25 years.
For children ages 6 to 17, Moderna found that two doses of its vaccine also provided an immune response similar to two doses in adults. Children ages 6 to 11 years received 50 microgram vaccines and adolescents ages 12 to 17 years received 100 microgram vaccines.
The vaccine trials were carried out at different times, when different variants of coronavirus were circulating. Although the FDA did not require vaccine manufacturers to submit vaccine efficacy data for approval, Moderna’s vaccine was estimated to be 93.3% effective against symptomatic disease in children 12 to 17 years of age during a time when the original coronavirus and the Alpha variant were dominant. The vaccine was estimated to have 76.8% efficacy against symptomatic COVID-19 for children aged 6 to 11 years during a time when the delta variant was predominant. However, the FDA also noted that for children ages 6 to 11, “the efficacy of the vaccine could not be reliably determined due to the small number of COVID-19 cases accumulated during the study.”
The vaccine was tested in children aged 6 months to 5 years during a time when the omicron variant was dominant. It was estimated to have 36.8% efficacy against symptomatic disease in children 2 to 5 years of age and 50.6% protection against symptomatic disease in children 6 to 23 months of age.
Vaccine efficacy estimates “for each age cohort were generally consistent” with what has been observed in adults, the FDA said.
The vaccine was also found to be safe in all age groups. Adverse reactions were “mostly mild to moderate in severity, generally of short duration, and occurred more frequently… after dose 2 than after dose 1.”
Injection site pain was the most commonly reported adverse reaction and the paper said that serious adverse events were rare and did not raise any concerns. No deaths were reported.
While there were no known cases of myocarditis or pedicarditis (inflammation of the heart) among trial participants, it is one of the known risks of Moderna’s COVID-19 vaccine, especially among men ages 18 to 24.
What’s next for Moderna’s vaccine?
FDA Vaccines and Related Biologics Advisory Committee meeting will review Moderna’s COVID-19 vaccines for children ages 6-17 on June 14 and review Moderna’s COVID-19 vaccines for children ages 6 months to 5 years on June 15.
Pfizer’s covid-19 vaccine for children under 5 will also be discussed on June 15.
After a vote by FDA vaccine advisers, the agency must decide whether to license the vaccines. The shots cannot be given until vaccine advisers at the US Centers for Disease Control and Prevention have voted to recommend the shots and the CDC director has approved the recommendation. The White House has said that vaccines for the youngest age group could be given as early as the week of June 20.