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Two 50-µg doses of the mRNA-1273 vaccine are safe and effective for children aged 6 to 11 years, according to a study published online May 11 in the New England Journal of Medicine.
C. Buddy Creech, M.D., M.P.H., from Vanderbilt University Medical Center in Nashville, Tennessee, and colleagues examined the safety, immunogenicity, and efficacy of the mRNA-1273 vaccine in children aged 6 to 11 years. In part 1, 751 children received 50- or 100-µg injections of the mRNA-1273 vaccine; based on the safety and immunogenicity results, 50 µg was selected for part 2. In part 2, 4,016 children were randomly assigned to receive two injections of 50 µg of mRNA-1273 or placebo in a 3:1 ratio, administered 28 days apart.
The researchers found that the dose level selected was associated with mainly low-grade, transient adverse events, most often injection-site pain, headache, and fatigue. As of the data cutoff, there were no reports of vaccine-related serious adverse events, multisystem inflammatory syndrome in children, myocarditis, or pericarditis. The neutralizing antibody titer in children who received mRNA-1273 at 50 µg was 1,610 at one month after the second injection compared with 1,300 for young adults who received 100 µg; in both age groups, serologic responses occurred in at least 99.0 percent of participants. At a time when delta was the dominant circulating variant, the estimated vaccine efficacy was 88.0 percent against COVID-19 occurring 14 days or more after the first injection.
“The trial results indicate that a 50-μg dose level of the mRNA-1273 vaccine had an acceptable safety profile and was efficacious in children 6 to 11 years of age,” the authors write.
Several authors disclosed financial ties to pharmaceutical companies, including Moderna.