Why children in Canada won't receive a coronavirus vaccine immediately

Canadian children and teens may have to wait to get any vaccines to protect people against COVID-19 because so few kids have been part of the clinical trials to test the immunizations so far.

Babies, children and teens aren't just small adults who can receive vaccines in the same way as adults, medical experts say.

Earlier this week, Dr. Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, said on NBC's Meet the Press that it could take months before those younger than 18 in the U.S. general public could get a coronavirus vaccine, if approved by regulators.

Dr. Sally Goza, president of the American Academy of Pediatrics (AAP), said children have suffered in numerous ways during the pandemic, including disruptions to their education, harms to their mental and emotional health as well as reduced access to critical medical services.

The AAP wrote an open letter to federal health officials in the U.S. to call on researchers to act quickly to ensure children are not left out of vaccine efforts.

There is currently no human pediatric data for vaccine candidates to protect against COVID-19, said Dr. Anne Pham-Huy, who sits on the National Advisory Committee on Immunization that provides independent advice to federal health officials on the use of vaccines in Canada.

Here are some questions and answers about the potential rollout of pediatric vaccines in Canada.

Are vaccine makers testing candidates in children and teens?

Yes.

The pharmaceutical company Pfizer, which is developing a coronavirus vaccine with German partner BioNTech, announced in October they were expanding testing of their vaccine trials to those 12 and older.

Moderna CEO Stephane Bancel told CNBC on Monday that the company expects to test the vaccine on children between the ages of 12 and 17 later this year and on younger children in 2021.

Pham-Huy, a pediatric infectious disease specialist in Ottawa, said companies in China have opened their coronavirus vaccine studies to children as young as three years old.

Why do the vaccines need to be tested in children and teens?

Immunology experts say the coronavirus vaccine candidates can't be widely given to babies, kids and teens until the vaccines are tested specifically in pediatric volunteers because:

• Their immune systems are more active than adults.

• Children often show stronger immune reactions to vaccines than grown-ups.

• The immune system matures from infancy through childhood and adolescence.

Why test in adults first?

Shannon McDonald, an assistant professor in the faculty of nursing at the University of Alberta, does public health research, including on vaccines. McDonald said it's not unusual to test vaccines on adults before kids.

"Children often will need either a slightly different formulation or a smaller dose of a vaccine, so it's appropriate to ensure the vaccine is safe and effective in adults and then move on to that testing," McDonald said.

When will the pediatric vaccine trials be done?

Dr. Joanne Langley co-leads Canada's vaccine task force. She's also a pediatric infectious disease specialist at Dalhousie University in Halifax where, clinical trials for vaccines like one for Ebola were first tested.

"As a study site in the Canadian Immunization Research Network, we have been approached by companies who are planning trials in children and in pregnant women." Langley said.

"We expect those will be expedited and that they will start in 2021."

Pham-Huy said she hopes some pediatric vaccine data will start to become available worldwide in the next six months.

Would immunizing adults also protect kids?

That's not yet known.

"Some vaccines contribute to herd immunity because the person who gets the vaccine doesn't spread any infection," Langley said. "We don't know for sure yet whether that occurs with the COVID vaccines and how effective it is."

Those who get vaccinated are less likely to be severely ill, she said.

Children generally don't get severely ill from COVID-19. Why do they need the shots?

Federal statistics show at 8.1 million, children and teens make up one-fifth of Canada's population.

While about 1.4 per cent of COVID-19 hospitalizations have been pediatric, those aged 19 and under account for more than 15 per cent of cases, or 50,000 infections, according to Statistics Canada.

"Although children don't have the severe lung problems that adults do with COVID-19, they do have important illness and so I think it's as important to prevent children from getting illness as it is for adults," Langley said.