TORONTO -- Amid the early stages of Canada’s COVID-19 vaccine rollout, it’s clear children have been put on the back burner.

In most Canadian provinces, children will only be vaccinated in the later stages of their vaccine rollout plans and the lone vaccine currently approved in Canada is not approved for children under the age of 16.

Still, questions swirl around the vaccine’s access, safety and timeline when it comes to Canada’s children receiving their protection from the disease.

CTVNews.ca spoke with two infectious disease specialists to answer some of the questions parents might have when it comes to the vaccine rollout for their children.

WHY ISN’T THE VACCINE APPROVED FOR CHILDREN?

The Pfizer-BioNTech COVID-19 vaccine approved in Canada is currently only available for Canadians ages 16 and older. The reason for this caveat is simple and involves two main factors: children are less impacted by the disease and clinical trials are prioritizing adults.

According to Health Canada, the vaccine’s “safety and effectiveness in people younger than 16 years of age have not yet been established.” In fact, last week, Pfizer-BioNTech released the results of the Phase 3 clinical trials, which showed that among the 43,448 participants in the trial, not a single one was younger than 16.

“They can't really say this vaccine is recommended for an age group that hasn't been tested yet,” Dr. Anna Banerji, an infectious diseases pediatrician and associate professor of pediatrics at the University of Toronto, told CTVNews.ca in a phone interview.

Dr. Manish Sadarangani, director of the Vaccine Evaluation Center at the B.C. Children’s Hospital, recently told CTV News Channel vaccine trials initially focused on where it might be administered during the initial rollout, which left children off the list.

“The focus has been on adults, including older adults and individuals who have other health conditions, and not children, because they haven’t been as severely affected as the older adults,” he said. “As we learn more about the role that children have in this, I think their final position, if you like, in the priorities will be determined.”

According to the Public Health Agency of Canada, Canadians under the age of 19 represent 15.5 per cent of the country’s overall cases, but less than 0.1 per cent of the deaths, with only three recorded COVID-19 deaths in that age group as of Dec. 15.

The 19 and under demographic also represents just 1.5 per cent of overall COVID-19 hospitalizations and one per cent of intensive care unit admissions.

WHY ARE CHILDREN LESS AFFECTED BY COVID-19?

Sadarangani said it’s still unclear why children are less impacted by the COVID-19 disease, but the two prevailing theories are that there are fewer of the receptors in children that the virus that causes COVID-19 uses to cling on to the human body and that children may be exposed to several other coronaviruses in day-to-day life, giving them a defence from the disease.

“It’s possible that they may have partial protection against COVID-19, but right now these are just theories and I think there’s a lot to be done,” he said.

Banerji said that while children tend to have less severe symptoms, teenagers can have experiences similar to adults.

“In my patients, some teenagers have become long-haulers,” she said. “For the vast majority of young children, it's a relatively minor disease, but there are some exceptions.”

A COVID-19 long-hauler refers to a patient who experiences persistent symptoms of the virus for weeks or months longer than expected.

WHEN MIGHT CHILDREN BE VACCINATED IN CANDA?

The timeline for children becoming vaccinated in Canada depends on the results of clinical trials, availability of the vaccine and each province’s rollout of the drug, but targeting the start of the 2021-22 school year seems appropriate, according to the experts.

“I think the goal is to have something ready by the start of the next school year and I think that's a reasonable goal given the different companies are all at different phases,” said Dr. Fatima Kakkar, a pediatric infectious disease specialist at CHU Sainte-Justine in Montreal.

Prime Minister Justin Trudeau has previously said the goal is for every Canadian who wants the vaccine to be inoculated by September 2021, but Banerji suggests children may see approval much sooner.

“If there's a lot more companies that jump on board in the next little while, it might be even sooner than that,” she said.  “The more vaccines there are, I think the quicker we're going to have enough vaccines for all the Canadians that want it and hopefully get this under control.”

Kakkar added that we may see a scenario in which different age groups are approved at different times as results from clinical trials pour in. 

“I actually think it's going to be progressive and so far they’re well underway between the 12 and 15,” she said. “So I think that's actually the next age group.”

ARE TRIALS INCLUDING CHILDREN BEING CONDUCTED NOW?

Pfizer and Moderna Inc. have already received permission to test its vaccines among children in the U.S. as young as 12, while two pharmaceutical companies in China have already begun testing their vaccines in children as young as three.

Meanwhile several other companies -- including AstraZeneca, Johnson & Johnson and Novavax -- are planning to begin clinical trials among children in the near future.

ARE THERE REPORTS OF ADVERSE AFFECTS AMONG CHIILDREN?

Kakkar said there remains to be very little data when it comes to results of clinical trials among children, but to the best of her knowledge, there are no such reports of adverse effects from the vaccine.

“There’s so little data in children, but we haven't had any,” she said. 

WILL CHILDREN RECEIVE SMALLER DOSES?

Without the data from clinical trials, it is still too early to determine whether children will require a smaller dose of the COVID-19 vaccine, but Kakkar said it is an entirely possible scenario.

“They have a more robust immune response to the actual infection, so … they might potentially have a more robust immune response to the vaccine,” she said. “They might need lower doses and maybe even fewer doses, we don't know, but the response overall has been so different that it might be that children will have a different dose and maybe even a different dosing schedule.”

Offering different doses depending on age is a common practise among some vaccines.

According to the U.S. Centers for Disease Control and Prevention, children under the age of three receive half the normal dose of the influenza vaccine, while adults over the age of 65 receive an extra bit of vaccine.

Adults also receive greater quantities of the hepatitis A and hepatitis B vaccines.