OTTAWA -- Indoor birthday parties and maskless classrooms could be nearly within reach for kids now that Health Canada has approved the first COVID-19 vaccine for children aged five to 11 in Canada.

Pfizer and its partner BioNTech submitted a request for approval of a child-sized dose of its mRNA vaccine for COVID-19 on Oct. 18.

The companies say the results of their trials in children show comparable safety and efficacy to those recorded in a previous Pfizer-BioNTech study in people aged 16 to 25.

The vaccine was 90.7 per cent effective at preventing COVID-19 in children and no serious side-effects were identified, according to the regulator.

After a thorough review of the data, the department has determined the benefits of the vaccine for children between five and 11 years of age outweigh the risks, Health Canada said in a statement Friday.

"Overall this is very good news for adults and children alike," said Dr. Supriya Sharma, Health Canada's chief medical adviser, in reference to the growing number of COVID-19 cases among children during the fourth wave of the pandemic.

The kids' vaccine was approved with a three-week interval between doses, but the National Advisory Committee on Immunization has suggested at least eight weeks between doses. Evidence has shown that a longer interval between doses increases the efficacy of the drug, and may even reduce the risk of rare side-effects like inflammation of the heart.

NACI's advice is that children who do not have any conditions that would make vaccination risky may receive two doses.

The language is slightly less strong than that for 12 to 16-year-olds, who should receive the vaccine according to NACI.

The recommendation for younger kids will likely be strengthened over time, as more information becomes available, said Dr. Matthew Tunis, NACI executive secretary.

The Public Health Agency of Canada will launch media campaigns soon to encourage parents to get the vaccine for their kids, and will be working closely with pediatricians and other health-care providers, chief public health officer Dr. Theresa Tam said.

"It is very important that we support children and their caregivers, and making informed decisions about COVID 19 vaccination, while respecting their choices and pace of decision-making," said Tam.

Pfizer-BioNTech has changed the formulation of the pediatric vaccine slightly, so new vaccines must be delivered to Canada before children can receive a shot.

Canada is expecting an accelerated delivery of 2.9 million child-sized doses, enough for a first dose for every child in the five to 11 age group.

In a statement Friday, Pfizer said the doses would be shipped "imminently."

Provinces are poised and ready to start administrating doses as soon as they have them in hand.

While children are at a lower risk of severe outcomes related to COVID-19, some kids do get very sick, Tam said.

Officials also point to cases of multisystem inflammatory disease, long-COVID, and heart inflammation associated with COVID-19 among kids as reasons to get the kids the shot.

"Most of the outbreaks now that are reported to us are from the school and daycare setting and especially in primary school," Tam said. "So we know that school outbreaks and disruption to education has a big impact on children as well."

Meanwhile the risks of getting the vaccine are low, she said.

Main side-effects for children associated with the vaccine are the same as those for slightly older vaccine recipients, though they were less common in kids, aside from redness and swelling at the injection site.

Health Canada will require Pfizer-BioNTech to continue to report on ongoing studies and real-world use to monitor any issues related to the vaccine in children.

"Health Canada and the Public Health Agency of Canada will continue to closely monitor the safety of this vaccine, and will take action if any safety concerns are identified," the statement read.

The U.S. Food and Drug Administration approved the Pfizer-BioNTech vaccine for children on Oct. 29, and the United States has already vaccinated more than 2.5 million children.

Sharma said no safety issues have emerged during the U.S. rollout of the vaccine.

For now NACI suggests children wait at least 14 days before or after receiving another vaccine, such as the flu shot, to get the COVID-19 vaccine so that officials can more easily identify potential side-effects.

Health Canada is still reviewing Moderna's mRNA COVID-19 vaccine for children aged six to 11 years of age.

The Canadian government is also expected to announce Friday an easing of measures taken to prevent importing new cases across the border.

Federal ministers are set to discuss the changes at 1 p.m.

They are expected to do away with the rule that requires travellers taking short trips to the U.S. to present a negative molecular COVID-19 test in order to get back into the country.