U.S. kids could get Pfizer shots by Halloween, Canadian approval still uncertain
Health Canada says it expects data from Pfizer on pediatric shots 'in the coming months'
Pharmaceutical giant Pfizer and its partner BioNTech have submitted data on the effectiveness of their COVID-19 vaccine in children to U.S. regulators, clearing the way for a possible authorization by Halloween, according to a member of the company's board of directors.
Canadian parents likely will be waiting longer to secure shots for their kids, however, because Pfizer-BioNTech hasn't yet made a similar filing with Health Canada. That could mean pediatric doses won't be available north of the border until the final weeks of the year at the earliest.
And it's not just the regulatory review that could hold up the shots. Canada may also have to buy the pediatric-specific variety Pfizer has in development — which means the vaccine supply chain is still an open question.
The race is on to vaccinate the country's kids at a time when many Canadian schools are dealing with a wave of the highly contagious delta variant. As the health crisis morphs into a pandemic largely for the unvaccinated, kids are uniquely vulnerable because they don't have any access to a vaccine.
A Health Canada spokesperson said Wednesday the department "anticipates vaccine manufacturers to provide data in children in the coming months."
Pfizer said that work is already underway.
"We are continuing our discussions with Health Canada and preparing to make our submission, but I cannot confirm timelines yet. We will provide updates as soon as we have more to share on this subject," Pfizer spokesperson Christina Antoniou said in a statement to CBC News.
In an interview with CBC's Power & Politics, Scott Gottlieb, a former U.S. Food and Drug Administration (FDA) commissioner and a current Pfizer board member, said the company could get the green light for its pediatric shot in the American marketplace "as early as Halloween, or if it's gets pushed a little bit, maybe into mid-November" if the FDA agrees it is safe and effective for use among people 5 to 11 years of age.
"I don't have a sense of the timeline outside the United States," he said.
WATCH: Former FDA commissioner Scott Gottlieb talks about the need for booster shots
Last year, Pfizer started submitting data on its adult vaccine to Health Canada in October. Two months later, on December 9, Health Canada authorized its use. It's unclear if that two-month timeframe will be repeated with the pediatric product.
'Officials will work as quickly as they can'
A federal official familiar with the Canadian regulatory process told CBC News on background that "nothing is a guarantee at this point. They'll submit it when they submit it."
"Officials will work as quickly as they can but we can't compromise health and safety. We have to manage expectations. Just because they submit their data doesn't mean, two weeks later, that product will be out the door to the provinces and territories," the official said.
Speaking to reporters late last week, Dr. Theresa Tam, Canada's chief public health officer, said regulators have to be sure the product is safe before it can be widely disseminated to the nation's children.
"For the 12 to 17 year olds, so far those programs are going well. There's no specific safety concern. I do think seeing the safety data in the younger children is of paramount importance," she said.
WATCH: Tam talks about vaccines for children
Another possible roadblock for the Canadian immunization campaign is supply. While the country is still awash in Pfizer shots from earlier procurement efforts, the company is now marketing a separate pediatric version of its product because kids are expected to get a much smaller dose than adolescents and adults receive.
"We are working on a different presentation designed for pediatric use, which will be supplied for commercial use if authorized," the Pfizer spokesperson said.
Canada may have to buy new kids-only Pfizer shots
That means Canada may have to procure a new kids-only supply of shots to vaccinate the nearly six million people in the country under the age of 12.
A federal official said those details will be worked out as part of Health Canada's review process. "I don't suspect it's as easy as taking what we've already got in the warehouse," the official said. "That will come from their submission to the regulator."
The federal government signed a deal in April to get more shots from Pfizer — including, if necessary, the pediatric variety and reformulated booster shots for adults — but deliveries of this new batch aren't expected to start until sometime in the new year.
So even if Health Canada regulators authorize the product for children before Christmas, shots may not be ready for use until 2022.
The kids' product isn't different from what has been used among people age 12 and up for nearly a year — it's the same vaccine with an identical formulation — but children will get a lower dose.
After testing different dosing levels throughout its clinical trial process, Pfizer found it was best to give kids a 10-microgram dose rather than the 30 micrograms used in other groups. This smaller dose still generated a strong antibody response but also produced fewer side effects for young trial participants, compared to what they experienced with the larger dose currently in use.
"You want to find an optimal dose where you have an equivalent amount of antibodies produced but you want to minimize any vaccine side effects, like fevers and injection site reactions," Gottlieb said. "You're trying to test the lowest possible dose that will elicit an appropriate immune response."
Asked why regulators might have to authorize a new kids-specific vaccine product when there's already an existing supply of the Pfizer vaccine, Gottlieb said it's all about preventing possible contamination. It's not as easy as drawing a smaller amount of product from the vials we already have, he said.
"Typically you would want to introduce vials that have lower amounts of vaccine in it so that you're not going into it as much," he said.
"If you have a vial that's used for dispensing 30 micrograms and now you are dispensing 10 micrograms, you're pulling out a smaller amount each time you go in. You are going in and out of a vial with a needle, multiple times, more times, and that introduces the risk that you could introduce bacteria into the vials."