Canada's health authority authorized the use of Moderna's COVID-19 vaccine for children under the age of 5 on Thursday.

This means 1.7 million children, among Canada's population of 38 million, are now eligible to be inoculated against the coronavirus.

"After a thorough and independent scientific review of the evidence, Health Canada has determined that the benefits of this vaccine for children between 6 months and 5 years of age outweigh the potential risks," the agency said.

It said that in clinical trials the effectiveness of the regime for small kids was found to be similar to that observed in people aged 18 to 25.

"With this announcement, parents and caregivers now have an option to protect these very young children, a group at high risk of infection and where additional health prevention measures like wearing masks may not always be feasible," said Patricia Gauthier, president of Moderna's Canadian unit.

The green light comes a year and a half after the Moderna vaccine was approved in Canada for adults.

The country began COVID-19 vaccinations for children aged 5-11 back in November.

The United States launched its inoculation campaign for children under five in June.

Also Thursday, Ottawa reinstated mandatory random COVID-19 testing of air travelers arriving at the nation's four major airports – Montreal, Toronto, Calgary and Vancouver – after pausing the program last month.

"We need to keep border testing measures in place because that is how we track importation of the COVID-19 virus, and of new variants of concern," Health Minister Jean-Yves Duclos said in a statement.

Anyone testing positive must self-isolate for 10 days.