MONTREAL, Canada -- Pfizer-BioNTech submitted an authorization request to Health Canada on Monday for the use of its Covid-19 vaccine in children aged 5-11, the companies and the Canadian government said.

"This is the first submission Health Canada has received for the use of a Covid-19 vaccine in this younger age group," it said in a statement.

The authorization request is based on data from trials conducted on 2,268 children in this age group for whom the dosage was lowered to 10 micrograms per injection -- three times less than the standard dose -- which the company says is "the preferred dose" for 5-11 year olds.

This same Pfizer-BioNTech vaccine is approved in Canada for ages 12 and up.

Health Canada said that it will only authorize the use of the vaccine if the independent and thorough scientific review of all data submitted confirms that the benefits outweigh the risks with this group.

The Canadian ministry also indicated that other manufacturers also were testing their vaccines on children of different age groups.

Earlier this month, Pfizer and BioNTech laboratories made the same request for 5-11 year olds in the United States.

Childhood immunizations are raising questions around the world. Many countries vaccinate adolescents from the age of 12, but very few do so below that age.

In recent months, the World Health Organization (WHO) has insisted that the urgent issue was to immunize the population of poor countries before children and adolescents in rich countries.