Two 50 μg doses of Moderna’s vaccine mRNA-1273 was generally well tolerated in children ages 6-11, who generated antibody levels 1.5 times greater than young adults in the study, according to the company.

Interim data from the Phase 2/3 study (KidCOVE study) of its COVID-19 vaccine candidate mRNA-1273 in children 6 to under 12 years of age showed a robust neutralizing antibody response after two doses of mRNA-1273 at the 50 µg dose level with a favorable safety profile, the company said in a press release. Moderna plans to submit these data to the US FDA, European Medicines Agency (EMA) and other global regulators in the near term.

“We are encouraged by the immunogenicity and safety profile of mRNA-1273 in children aged 6 to under 12 years and are pleased that the study met its primary immunogenicity endpoints,” said Stéphane Bancel, Chief Executive Officer of Moderna. “We look forward to filing with regulators globally and remain committed to doing our part to help end the COVID-19 pandemic with a vaccine for adults and children of all ages.”

KidCOVE is a randomized, observer-blind, placebo-controlled expansion study to evaluate the safety, tolerability, reactogenicity and effectiveness of two 50 µg doses of mRNA-1273 given to healthy children 28 days apart. The study population is divided into 3 age groups (6 to <12 years, 2 to <6 years, and 6 months to <2 years). Today Moderna reports on the 6 to under 12 years of age cohort.

This cohort enrolled 4,753 participants who were 6 to less than 12 years of age. In the trial, the SARS-Cov-2-neutralizing antibody geometric mean ratio (GMR) comparing the response in children to the response in young adults from the Phase 3 COVE study was 1.5 (95% Cl: 1.3, 1.8), with a seroresponse rate of 99.3%, representing a difference of 0.6% (95% CI: -2.8%, 2.8%) to the Phase 3 benchmark. These results demonstrate strong immune response in this cohort of children one month after the second dose and met the co-primary immunogenicity endpoints for 6 to less than 12 years olds in KidCOVE.

mRNA-1273 was generally well tolerated with a safety and tolerability profile generally consistent with the Phase 3 COVE study in adolescents and adults. The majority of adverse events were mild or moderate in severity. The most common solicited adverse events were fatigue, headache, fever, and injection site pain.

Safety data continue to accrue, and the study continues to be monitored by an independent safety monitoring committee. All participants will be monitored for 12 months after their second injection to assess long-term protection and safety. These data are subject to change based on ongoing data collection. The Company plans to submit data from the KidCOVE study to a peer-reviewed publication.

The enrollment for the 6 years to under 12 years is complete, but the Phase 2/3 study continues to enroll children ages 6 months to under 6 years of age. The Company has enrolled approximately 5,700 pediatric participants in the U.S. and Canada in the trial as a whole. The study is being conducted in collaboration with the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH) and the Biomedical Advanced Research and Development Authority (BARDA), part of the Office of the Assistant Secretary for Preparedness and Response at the U.S. Department of Health and Human Services. The ClinicalTrials.gov identifier is NCT04796896.