Pfizer COVID-19 vaccine: How the shot differs for kids and adults

COVID-19 vaccines could be made available to kids aged as young as five in Canada in the coming months.

Pfizer officially submitted a request to Health Canada on Monday, seeking authorization for the use of its shots in children aged five to 11 years old.

In a statement, Health Canada said it will only give the green light after a thorough review of the data to make sure the benefits of the shots outweigh any potential risks for this age group.

While Pfizer’s COVID-19 vaccine targets the same virus, SARS-CoV-2, there are some notable differences for adults and kids, according to the drug maker.

The pediatric doses are one-third (10 micrograms) the size given to adults and teens aged 12 and older (30 mcg).

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If approved, each vial will contain 10 doses for the younger age group, said Christina Antoniou, director of corporate affairs at Pfizer Canada.

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This is different than the six doses per vial currently being used for adults and adolescents in Canada.

The kids’ vaccines will also have a unique label and different colour for the cap.

The variations in presentation and dosage are not unusual, experts say, as has been the case for other vaccines.

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“This would not be the first time that we actually see that a vaccine has to be dosed differently or even packaged differently for children,” said Dr. Shazeen Suleman, a pediatrician at Unity Health Toronto.

However, the formulation of the vaccine itself is the same, Antoniou confirmed to Global News in an emailed statement.

Drawing up pediatric doses from the existing vials for the adults is not recommended “for a number of reasons”, Dr. Theresa Tam, Canada’s chief public health officer, said during a news conference Friday.

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A spokesperson for Health Canada said the agency will inform Canadians of appropriate details once its review is completed.

Children also undergo three phases of the vaccine trials, but the sample size is not as large.

Because the efficacy of vaccines has already been tested in large-scale clinical trials among the adult population, the same steps are not needed for children.

As part of its trial, Pfizer and BioNTech said their data showed a strong immune response among 2,268 children ages five to 11.

Data showed the two-shot mRNA vaccine generated an immune response that matched what was observed in those aged 16 to 25.

While the federal government has a contract with Pfizer that includes pediatric shots, Ottawa is not yet saying how fast they will arrive, if and when the under-12 Pfizer vaccine gets the green light from Health Canada.

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— with files from Global News’ Abigail Bimman.