Health

Moderna to start testing vaccine on Canadian kids, but doses before next school year unlikely

Moderna says upcoming clinical trials for its COVID-19 vaccine will include Canadian children, but experts say it's unlikely students will receive one before the next school year in September.

Trials with younger participants tend to take more time, says Health Canada

Grade one students wear face masks as they attend class in Montreal on March 9. (Ryan Remiorz/The Canadian Press)

By most accounts, Canadian kids are not expected to receive a COVID-19 vaccine this year, let alone before the next school year in September. But a select few may be able to receive an early dose through clinical trials expected to launch in various locations.

Moderna said this week it wants to recruit an unspecified number of Canadian children aged six months to 12 years for upcoming trials of its COVID-19 vaccine, while Johnson & Johnson is poised to run trials for its vaccine with 12- to 17-year-olds.

Pediatrician and professor Dr. Jim Kellner of Alberta Children's Hospital says it's a great opportunity for Canada to play an important role in the COVID-19 effort, and can ultimately speed Health Canada's analysis when it comes time for the regulator to consider approving the vaccine for kids.

He notes that the regulator evaluates all data on their merits, but a Canadian trial with Canadian volunteers "won't hurt."

"I wouldn't expect that there's any (advantage) getting us to the front of the line, particularly, but what conducting the trials in Canada does is it will help Health Canada, for example, in its evaluation of the data," says Kellner, who sits on Canada's COVID-19 Immunity Task Force.

A vial of the Moderna COVID-19 vaccine is seen at a clinic in Thompson, Man., on Feb. 1. (Tyson Koschik/CBC)

In addition to Moderna, Canada has approved vaccines by Pfizer-BioNTech, AstraZeneca-Oxford and Johnson & Johnson for adult use, although the Pfizer product can be used by people as young as 16.

AstraZeneca has also started a trial with younger age groups, while this spring, Johnson & Johnson is expected to study its vaccine with volunteers aged 12- to 17-years-old in sites including Toronto and Burlington, Ont.

Full data from trials not expected until 2022

Dr. Caroline Quach, the chair of Canada's National Advisory Committee on Immunization (NACI), said Tuesday that a vaccine for kids wasn't expected before the end of the year, although trial data from Pfizer involving 12-to-15-year-olds could arrive in two-to-three months.

In the meantime, Kellner notes NACI has given clinicians some leeway to consider offering the Pfizer vaccine to 12-to-15-year-olds who have significant underlying conditions that put them at particular risk.

He says that decision was made by extrapolating data on vaccinated young adults, and suggested the same thing could be done to approve use in older kids when the data on teens becomes available.

"Adding in younger children could be done sequentially. It's not like we have to wait, I don't think, until all childhood ages have been tested before approving the vaccine," he said.

"Then the issue becomes: When does the data become available? And most of the vaccine companies are taking a sequential approach — teenagers first. Then once you've figured out teenagers you look at school aged children, sort of six to 11, and at the same time those are being figured out you look at younger children, five and under."

Earlier this month, Health Canada's Chief Medical Adviser Dr. Supriya Sharma also doubted that a vaccine would be ready for children by the time school starts in September, noting trials with younger participants tend to take more time.

"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," Sharma said.

Recruitment, retainment an issue with kids

Moderna has said its Phase 2/3 study would involve 6,750 healthy pediatric participants aged six months to 12 years. Initial participants are based in the United States but the biotech company said Canadian sites would be added as the trial progresses.

Initial participants are based in the United States, but Canadian sites will be added as the trial progresses.

Canadian sites have not yet been chosen for the Moderna trial, nor have Canadian participants.

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The trial will evaluate the safety and effectiveness of two doses given 28 days apart. Participants will be followed for one year after the second vaccination.

Recruitment and retainment is an issue with children, says Karri Venn, research president at LMC Manna, which will run J&J's teenage trials in Toronto and Burlington.

However, she allowed that interest could be different in the case of COVID-19. She said she suspected many families would be enticed by the possibility that enrolment in a trial could speed their teen or child's return to COVID-prohibited activities like group sports.

Middle school students wearing face masks are seen working outside during an inclusion and anti-racism class in Abbotsford, B.C., in November 2020. (Maggie MacPherson/CBC)

Venn said her firm expects to begin its COVID-19 vaccine trials in May, but protocols have not yet been approved, delaying recruitment.

She said LMC Manna would not be interested in running a clinical trial for younger kids.

"We're comfortable [with] 12 and up because you can actually have conversations with them, they're a part of the process when you go through it," says Venn. "But having an infant or a six-year-old, asking them to do blood work — not easy, right? And there's still so much growth and development during those stages."

A blood sample is taken from a Moderna COVID-19 vaccine study participant in Miami in September 2020. (Taimy Alvarez/The Associated Press)

Kellner says children too young to give consent must still give their assent, which isn't complete consent but reflects a child's willingness to take part in the study. That's in addition to securing their parents' agreement.

And just as with adult trials, participants can leave at any time, for any reason.

Kellner estimates the dropout rate among kids and teens to be between 10 and 15 per cent, depending on the demands of the trial.

Kindergarten students wear face masks in Toronto on Feb. 25. (Evan Mitsui/CBC)

He says trials like the proposed Moderna study typically require blood to be drawn from participants before and after each dose.

"At a minimum, you'd probably be looking at four blood tests for a two-dose vaccine."

A local ethics board will produce guidelines on how much blood is acceptable to draw from a child, which will depend on their size, he said.

Kellner says he's been doing vaccine clinical trials with children for more than 20 years and does not find it difficult to find volunteers.

"Canadian families are amazingly enthusiastic and willing to participate in important clinical trials that will help lead to things like safe and effective vaccines. It's quite inspiring, actually."

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