The results of a large Phase 3 trial testing Moderna’s COVID-19 vaccine in 12 to 17 year olds have been published in The New England Journal of Medicine. The study indicates the vaccine is as safe and effective as it was previously found to be in adults.
The trial followed close to 4,000 young subjects aged between 12 and 17. The cohort was administered the same vaccine protocol and dose as previously tested and approved in adults.
As with previous trials, the most common side effects were injection site discomfort, headache and fatigue. No serious adverse effects were seen in the trial, and incidences of mild side effects were similar across all ages.
Mild heart inflammation has been previously noted as a potential rare side effect of mRNA COVID-19 vaccines, primarily in young men. This trial did not detect any cases of myocarditis or pericarditis but it also notes these events are estimated to appear in around 13 cases per million doses, so it was expected to be too rare to arise in this trial.
Serology testing revealed the immune response in young subjects is similar to that seen in adults. The researchers say that because COVID-19 incidence is less in adolescents this trial lowered the bar for defining a positive case. Just one symptom was used to categorize a symptomatic infection. Based on that lowered metric the trial still found no symptomatic cases after two vaccine doses, suggesting the vaccine is incredibly effective in adolescents.
“The number of documented cases of Covid-19 is too small to generate robust assessments of vaccine efficacy,” the researchers cautiously note in the study “However, it appears that the mRNA-1273 vaccine safely induced levels of antiviral antibodies that should be protective against SARS-CoV-2 infection.”
Moderna first announced this trial data back in May before it was subsequently peer-reviewed and published. At the time Moderna indicated it would be submitting this data to regulatory bodies around the world.
In late July the European Medicines Agency approved use of Moderna’s vaccine in 12 to 17 year olds. However, the US Food and Drug Administration (FDA) has yet to issue an emergency use authorization for the vaccine in teenagers, despite approving Pfizer’s similar mRNA vaccine for that age group back in April.
Both Pfizer and Moderna are currently testing their mRNA vaccines in under 12 age groups. Based on concerns over rare side effects the FDA has recently requested both companies expand the size of those trials to include greater numbers of children.
These ongoing trials are split into three age groups: five to 11, two to five, and six months to two. Pfizer’s trials are slightly more progressed than Moderna’s, with preliminary data for the five to 11 year old age group expected as early as September.
The new research was published in The New England Journal of Medicine.
