New research shows the majority of Canadian children and teens were spared the most severe health outcomes of COVID-19 in the first phase of the pandemic.

But health experts are concerned the increased transmissibility of the Delta variant could expose high numbers of vulnerable young people to the virus and lead to more serious cases.

The study, published Monday in the Canadian Medical Association Journal, found that pediatric hospitalizations linked to COVID-19 were low from March to December of last year.

In addition, about 4 in 10 children who were in hospital with COVID-19 had been admitted for reasons unrelated to the new coronavirus. And children and teens who were hospitalized for severe illness linked to COVID-19 often had existing health problems, such as obesity and chronic neurologic, or lung conditions other than asthma.

With the highly transmissible Delta variant now accounting for most cases in Canada and no vaccine yet approved for children under 12, experts say more needs to be done to protect young people from the virus.

But there is good news on vaccines for those aged 5 to 11.

The head of Pfizer says they’re just days away from petitioning the U.S. Food and Drug Administration to approve its COVID vaccine for children aged 5 to 11.

“It’s a question of days, not weeks and then it is up to the FDA to be able to review the data and come to their conclusions and approve it or not,” said Pfizer President and CEO Dr. Albert Bourla.

Pfizer representatives are also expected to follow up with a request for approval by Health Canada.

The children’s dose is a third of the strength of the adult dose, but Pfizer scientists say their research shows the same formation of antibodies in kids, that a full dose creates in adults.