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Kids ride their bikes past the sign for D.A. Morrison school in Toronto on June 2, 2021. COVID-19 vaccination rates among eligible age groups are steadily climbing in Canada, leaving children to become the least protected from infection.Frank Gunn/The Canadian Press

Children and teenagers account for the largest group of COVID-19 cases in the country, raising questions about their risk of exposure as restrictions ease.

Vaccination rates among eligible age groups are steadily climbing, leaving children to become the least protected from infection. Health Canada has approved the Pfizer COVID-19 vaccine for only those 12 and older and the Moderna vaccine for only individuals 18 and older, though trials for younger children are under way.

Some experts say the benefits of easing public-health restrictions, such as lockdowns and school closings, will likely outweigh the risks of infection to children, since COVID-19 tends to be mild in children, amounting to nothing more serious than the common cold in most.

Now that adults, who tend to get sicker, have had the chance to get vaccinated, COVID-19 “kind of becomes like influenza,” said Joan Robinson, a professor in the department of pediatrics at the University of Alberta. “We would never consider shutting all of society down during influenza season to prevent that morbidity and mortality because it’s simply not worth the trade-off. And I think in future years, that will be what COVID-19 will look like.”

According to the most recent government data, as of June 18, those ages 19 and under make up 19.2 per cent of COVID-19 cases in Canada, narrowly edging out the 20- to 29-year-olds to account for the greatest share of cases. And in some recent outbreak clusters, children and teens, who are not yet eligible for vaccination or were only partly vaccinated, have accounted for a large proportion of cases. In Northern Ontario, for example, when there were 216 active COVID-19 cases in Kashechewan First Nation last week, 105 of them were among children under age 12.

But how children are affected by COVID-19 has remained fairly consistent throughout the pandemic, even with the introduction of new, more transmissible variants of the SARS-CoV-2 virus, said Shaun Morris, clinician-scientist in the division of infectious diseases at the Hospital for Sick Children in Toronto. Many children have no symptoms at all, or very few symptoms, most commonly cough, runny nose, fever and loss of appetite, he said.

If a child is sick enough to be admitted to hospital, it’s usually because their respiratory symptoms have worsened and they need to be monitored or they require oxygen, Dr. Morris said.

Government data show 1.8 per cent of COVID-19 hospitalizations since the start of the pandemic have been among those 19 and under. There have been 13 deaths in this age group, accounting for 0.1 per cent of all COVID-19 deaths.

The coronavirus will likely never disappear completely, and will continue to circulate in Canada and elsewhere, Dr. Morris says. As the vaccine rollout continues, the threat of COVID-19 to children will depend on how much of the virus is circulating in the community and, at an individual level, on factors such as who children are interacting with, he said. But even if more children get infected than adults, they will still be at lower risk of severe disease and severe outcomes, he said.

“Once community transmission, overall, is brought to a very low level, I think other than immunizing their children when their children are eligible to be immunized and following general public-health guidance, I don’t think it’s something that parents need to disproportionately worry about,” he said.

Nevertheless, there still are many unknowns when it comes to the impact of COVID-19 on children.

The relatively small number children who are admitted to hospital and who require intensive care tend to have underlying conditions, Dr. Robinson said. But while obesity appears to be an important risk factor, it’s still unclear which risk factors increase the incidence of hospital admissions the most, she said.

In rare instances, children also develop a condition called multisystem inflammatory syndrome (MIS-C), which is believed to be linked to COVID-19. This syndrome, which tends to arise two to eight weeks after infection, involves an “overexuberant” immune response, causing inflammation throughout the body, Dr. Robinson explained. In Alberta, more than 50 children have been hospitalized with MIS-C, at least half of whom were treated in intensive care, and most have recovered quickly, she said.

However, since no one knows for sure how many children have ever been infected with the coronavirus, it’s unknown what percentage of children actually end up in hospital or develop MIS-C, she said.

Similarly, a relatively small number of children experience long-haul symptoms, but experts say the prevalence is not known.

At the University of Michigan Health C.S. Mott Children’s Hospital, pediatric pulmonologist Ixsy Ramirez said a pediatric post-COVID syndrome clinic, which opened this spring, has been receiving about four to six referrals a week. The clinic sees children who have had a COVID-19 diagnosis and whose symptoms have not gone away after at least 60 days.

Dr. Ramirez said patients have symptoms that range widely in severity and commonly include cough, shortness of breath and fatigue. Most of them are teenagers, who were previously healthy. Some have difficulty with simple tasks, such as walking up stairs without becoming winded, while others find they can’t play sports like they used to, she said.

Even though children seem to be less likely to have long-haul symptoms than adults, they still need to take precautions against catching COVID-19, she said. “I don’t think that necessarily means, ‘Okay, we just throw caution to the wind and they’re okay to do as they please.’”

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