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Moderna starts COVID-19 vaccine trial in infants and young children

two boys in face masks bump elbows while standing near a wall in school
(Image credit: Getty/Westend61)

Moderna has begun testing its COVID-19 vaccine in children as young as 6 months old and up to 11 years old, the company announced. 

The trial includes healthy children in the U.S. and Canada and will be conducted in two parts, according to a statement from the company. In the first stage, the company will test how the participants respond to different dose levels of the vaccine. Children older than 2 years old may receive 50 or 100 micrograms of vaccine per dose, while children younger than 2 may receive 25, 50 or 100 micrograms. Each child will receive two doses in total, with each dose given 28 days apart, the same spacing as the shots given to adults.

The first children vaccinated in each group will receive the lowest dose of vaccine, so that the trial organizers can watch for side effects before giving higher doses to other children, The New York Times reported

Related: Quick guide: COVID-19 vaccines in use and how they work 

Following stage one, Moderna will perform an interim analysis to determine which dose level is appropriate for each age group. Children enrolled in the second stage of the trial will receive either the dose selected through this analysis or placebo shots of saline, according to ClinicalTrials.gov.  

The trial participants will be monitored for a year following their shots, in order to track their side effects, antibody levels and cases of COVID-19 infection. Based on the antibody levels and the relative rate of infection between the vaccinated and placebo groups, Moderna will calculate how protective the shots are for babies and young kids. They'll be using the antibody counts as the primary measure of protection, while also taking infection rates into account.

The Moderna vaccine, called mRNA-1273, does not contain the coronavirus itself and cannot cause COVID-19. It instead contains a molecule called mRNA that, once inside the body, tells cells to build part of the virus called the spike protein. The immune system then learns to recognize the spike and target it for destruction.  

"We are encouraged by the primary analysis of the Phase 3 COVE study of mRNA-1273 in adults ages 18 and above," Stéphane Bancel, chief executive officer of Moderna, said in the company statement. "This pediatric study will help us assess the potential safety and immunogenicity of our COVID-19 vaccine candidate in this important younger age population." 

Moderna estimates that 6,750 participants will ultimately be enrolled in the trial, according to its trial recruitment website. The company is currently conducting a trial of 3,000 children age 12 to 17, the Times reported. This trial also includes a year of follow up and will likely be completed in June 2022, according to ClinicalTrials.gov.  The vaccine could potentially be cleared for emergency use in kids before this time period is up, but it's unknown when or if that might occur. 

Originally published on Live Science. 

Nicoletta Lanese
Nicoletta Lanese is a science journalist and dancer who aims to bring science to new audiences, whether in print or on stage. She holds degrees in neuroscience and dance from the University of Florida and a graduate certificate in science communication from the University of California, Santa Cruz. Brains are her beat. Follow her on Twitter @NicolettaML.