CHEO sees record number of patients with non-COVID respiratory virus

Eastern Ontario's children's hospital, CHEO, says it's seeing an early resurgence of a respiratory virus, unrelated to COVID-19, that caused a record number of patient admissions in October.

In October, CHEO admitted 37 patients with respiratory syncytial virus (RSV), the highest number on record for that month, and more than double the previous high of 15 cases.

RSV is a virus that can lead to serious illnesses such as bronchiolitis and pneumonia. Common symptoms include wheezing, lethargy and a persistent cough.

Tammy DeGiovanni, CHEO's vice-president of clinical services, said the hospital usually doesn't see this amount of RSV patients until the winter months.

"Typically in October we'll see between two and three cases," she said. "[It's] very unusual that we see that number this early on in the year."

The spike in RSV cases at CHEO is a continuing trend that began this summer when pandemic measures began to ease.

DeGiovanni said more human interaction could be a cause of the increased RSV spread, especially following a winter where those pandemic measures would have limited the spread of the virus.

"We've all been masking, doing very good hand-washing, not mixing as much as we have in other years," she said.

Less exposure means less immunity

Dr. Pascal Lavoie, a pediatrician and clinician scientist at the B.C. Children's Hospital Research Institute in Vancouver,  said less exposure means people started to lose antibodies to certain viruses, including RSV.

"Our immunity against some viruses has gone down simply because, for some viruses, our protection depends on being repeatedly exposed," he said.

Dr. Lavoie said RSV affects children more than adults because they have had less exposure in their shorter life spans. The concern is even greater for infants if their mothers have had less exposure and didn't pass on antibodies during childbirth, Lavoie said.

DeGiovanni said RSV patients at CHEO are mostly infants and toddlers who have contracted the virus from older siblings at daycare or a friend's house.

"[They] bring it home to infants that have had less of an immunity and haven't developed that immunity over time," she said.

Hospitals in B.C. and Quebec have seen RSV patient spikes similar to CHEO.

Lavoie said it remains to be seen if more cases could occur during the winter when RSV usually spreads, or if the spike early in the season could limit the amount of cases as the population regains immunity.

"Until this happens we have to be careful," he said. "If [the trend in cases] continues, it's going to be a tough winter."