Ontario’s chief medical officer of health waded into the controversial issue of “immunity debt” Thursday, saying the issue needs more study but it makes sense to him thatpandemic public health measures such as masking are a factor in the record numbers of young children becoming seriously ill with respiratory viruses this year.


Partly because of that, Dr. Kieran Moore ruled out any new mask mandates in the province unless COVID-19 changes significantly and vaccines and treatments are no longer effective.

“Masking was one of our only tools when we didn’t have vaccines and we didn’t have oral outpatient treatments like Paxlovid. It was something we were dependent upon, but we are obviously seeing that there are somenegative consequences to not being exposed to the normal respiratory pathogens over time,” he said during an interview with this newspaper.

“I don’t know if at a societal level we are ready to go back” to mask mandates, he added.

The theory, which has been widely criticized by some experts, is thatpublic health measures were so effective at stopping COVID-19 and many other seasonal viruses that it has left very young children especially highly susceptible this yearnow that mandates have been lifted and more viruses are circulating. It counters some evidence that exposure to COVID is affecting some peoples’ immune cells and weakening their immunity. Moore said it makes sense that people with Long COVID have some kind of immune dysregulation and the province is reviewing the hypothesis.

But he said his personal belief is that “we have more susceptible children that have not been exposed previously and that is causing this rise”. He added thatmasking will always be an important public health tool when unknown pathogens are spreading and there are no other tools available, because it works, “but once we have therapeutics and vaccines, continued masking can decrease our overall immunity to other viruses. That is a lesson I think we are learning.”

In recent weeks, the Red Cross has been deployed to assist at CHEO, hundreds of pediatric surgeries have been cancelled across the province, children have had to be airlifted hundreds of kilometres from home for critical care and one pediatric surgery chief said he feared some children won’t make it because of dangerously long waits for needed surgery. In Ottawa and elsewhere, children’s health officials have pleaded with people to wear masks to protect children and the hospital system.

Moore confirmed that at least two children, between 10 and 13, have died of influenza this fall in the province and that several other pediatric deaths are being investigated as possibly related to influenza. He said there are indications that the current influenza surge has peaked.

Respiratory syncytial virus (RSV), which has landed record numbers of young children, as well as dozens of people over 65, in hospital, is continuing its steady surge in the province, he said.

Moore said the province is also closely watching cases of invasive group A strep in children in the province. There have been 18 cases reported among children 14 and under since September, he said. There have been no fatalities associated with the illnesses, but Moore said provincial officials are monitoring the situation daily. Group A strep is a bacterial infection of the throat or skin that can cause scarlet fever and, in its invasive form, can get into the blood stream and cause death. In the U.K., at least seven children have died from invasive group A strep in recent weeks, and dozens of cases of scarlet fever have been reported. Several European countries have also seen higher than normal cases. Moore said data is still being analyzed but it doesn’t appear there are more cases in Ontario this year than in pre-COVID years.

"...masking will always be an important public health tool when unknown pathogens are spreading and there are no other tools available, because it works, “but once we have therapeutics and vaccines, continued masking can decrease our overall immunity to other viruses. That is a lesson I think we are learning.”