The study will assess the safety and effectiveness of two doses of the shot, given 28 days apart, and intends to enroll about 6,750 children in the United States and Canada.
The vaccine has already been authorized for emergency use in Canada and the U.S. for those who are aged 18 and older.
In a separate study which began in December, Moderna is also testing its vaccine in adolescents between 12 and 18 years old.
The latest study is being conducted in collaboration with the National Institute of Allergy and Infectious Diseases (NIAID) and the Biomedical Advanced Research and Development Authority (BARDA).
When will kids be able to get the COVID-19 vaccine? Experts weigh in
At this point in Canada, no vaccines have been approved for use in children younger than 16 years of age.
The Pfizer-BioNTech vaccine can be used in anyone 16 and older, Health Canada says, while the other three shots — Moderna, AstraZeneca, and Johnson & Johnson — have been approved for adults 18 and up.
Health Canada says it is waiting on data from the vaccine manufacturers before it approves any shot for use in children.
Dr. Supriya Sharma, Health Canada’s chief medical advisor, said Pfizer and Moderna’s clinical trials in younger-age adults are the furthest along so far, but acknowledged that Johnson & Johnson has also been given Health Canada’s seal of approval to test the safety and efficacy of its vaccine in children aged 12 to 17.
AstraZeneca has also started its own clinical trial to test its vaccine in younger age groups, though Sharma is convinced Health Canada will receive data from Pfizer and Moderna first.
When asked whether Health Canada could approve a vaccine for use in children before school begins in the fall of 2021, Sharma said the timeline sounded “a bit optimistic.”
“So the trials in children tend to be a bit slower to get up and running in terms of recruiting individuals,” she said. “And then, of course, we have to conduct the trials and then take that information and assess that.”
She said it’s “not inconceivable that we might have some data in the summer.”
“And potentially by the end of this calendar year, we might have some indications in children, but … that’s still pretty optimistic.”
Montreal pediatric specialist answers questions about the coronavirus and kids
That appeared to be echoed by Dr. Caroline Quach, the chair of Canada’s National Advisory Committee on Immunizations, on Tuesday. She said data has been provided by Pfizer on the 12 to 15 age group.
However, NACI will not make any recommendations on vaccines used in children before it has seen data from a phase three trial, she said.
“From our understanding, we should get some data in the next two to three months for at least eh 12 to 15-year-olds. Then, as data is accrued and vaccines are deemed to be safe and immunogenic, then they will decrease in age range until they go down to the younger ones,” she said.
“But we’re not expecting anything for children before the end of 2021.”
— with files from Global News’ Hannah Jackson and Rachael D’Amore