Washington: Moderna Inc. said it has begun delivering experimental doses of its COVID-19 vaccine to children as part of a study to determine whether it is safe and effective in those as young as 6 months.
The trial aims to enroll about 6,750 volunteers in the US and Canada. The National Institute of Allergy and Infectious Diseases and the Biomedical Advanced Research and Development Authority are collaborating with the company, Moderna said in a statement.
In the first stage of the trial, researchers will test various doses of vaccine to see which works best. Study participants between the ages of 2 and 11 will receive either 50 or 100 micrograms per dose, while those ages 6 months to just under 24 months will get 25, 50 or 100 micrograms per dose.
All doses will be administered twice, 28 days apart.
For the sake of comparison, each Moderna dose for adults contains 0.5 milliliters of vaccine. That’s equivalent to 500 micrograms.
Researchers will analyze the data from the first phase of the trial to determine which doses to give to children and toddlers in the second phase of the study. In that part of the study, participants will be randomly assigned to receive either the vaccine or a saline placebo. Then they’ll be tracked for a year to see whether the vaccine works better than the dummy shots.
Vaccine efficacy will be assessed through one of two ways.
If it turns out that the risk of developing COVID-19 is significantly lower among children who get the vaccine than among children who get the placebo, the researchers will be able to compare those two groups and calculate the amount that the risk is reduced as a result of getting the vaccine. The more the risk is reduced, the more effective the vaccine.
However, COVID-19 is less likely to strike children than adults. Although children make up about 22% of the US population, they account for just 11.6% of COVID-19 cases, according to data from the Centres for Disease Control and Prevention. And cases for all age groups, including children, are expected to fall as vaccines roll out to adults and the country gets closer to achieving herd immunity.
Those factors may mean that there won’t be enough cases of COVID-19 among clinical trial participants for researchers to make a statistically significant calculation of vaccine efficacy. In that case, the study team will also examine the immune response of kids in the trial and compare it to that of adults. If the kids generate enough antibodies compared to adults, the researchers will take that as evidence of vaccine effectiveness.
The trial is expected to continue through June 2023.
Pfizer and BioNTech are currently testing their COVID-19 vaccine in children as young as 12. Their initial clinical trial included 16- and 17-year-olds, and the vaccine is currently the only one authorized for use in minors in the US.
Johnson & Johnson plans to test both single and two-dose regimens of its vaccine in children ages 12 to 17, according the Food and Drug Administration.