RSV-related hospitalizations among children in Canada doubled in 2022–2023

Hospitalizations caused by respiratory syncytial virus (RSV) more than doubled in 2022–2023 compared to the years preceding the pandemic, according to a new study conducted by researchers at the research institute of the McGill University Health Centre and the BC Children’s Hospital Research Institute.

More than 5,000 hospitalizations were recorded during that period, and infants under six months of age—who are particularly at risk of complications—accounted for the majority of intensive care admissions, overwhelming the capacity of Canadian pediatric hospitals, the researchers warn.

“What we saw in 2022–2023 was truly unprecedented,” said the study’s co-lead author, Jesse Papenburg, a pediatric infectious disease specialist at the Montreal Children’s Hospital. “We observed that RSV-related hospitalizations among children doubled compared to pre-pandemic annual averages, and we saw the same trend for intensive care admissions.”

These spikes, he added, are all the more remarkable “because the RSV season lasts only a few weeks or months, so it put enormous pressure on healthcare systems across Canada—particularly in pediatrics—in late fall 2022 and early winter 2023.”

Year in and year out, RSV is the leading cause of lower respiratory tract infections in children, such as bronchiolitis or pneumonia, according to a press release. More than 75 per cent of RSV-related pediatric hospitalizations occur in otherwise healthy children.

The study recorded 5,362 RSV-related hospitalizations during the 2022–2023 season, compared to an annual average of 2,517 for the period from 2017 to 2019.

“The very high demand was felt by frontline workers, but our study is the first to quantify and document it at the national level for tertiary hospitals across Canada,” said Papenburg.

The study’s authors believe this increase is attributable to the lifting of lockdown measures, which delayed children’s initial exposure to RSV. They also noted that the average age of children hospitalized due to RSV was slightly higher during the 2022–2023 season.

Despite all these “unusual” characteristics, Papenburg noted, “we saw that the age group hardest hit was infants in their first few months of life.”

“Children under six months of age accounted for more than 40 per cent of hospitalizations,” he said. “But on top of that, they accounted for more than 60 per cent of intensive care admissions, so this age group is truly overrepresented not only in terms of the risk of hospitalization, but also as the sickest children requiring critical care.”

These data are crucial, he noted, since RSV vaccination programs specifically target pregnant women—to provide passive immunity to the baby—and infants under six months of age.

“This illustrates the burden that can be prevented with these interventions,” said Papenburg.

New tools for preventing RSV are now available in Canada. These include long-acting monoclonal antibodies—synthetic proteins that offer temporary protection against infection—and a vaccine administered during pregnancy to protect babies during their first months of life.

RSV should not be taken lightly, Papenburg cautioned. Of the ten children he sends to the hospital in Canada each year, eight had no specific risk factors, comorbidities, or underlying medical conditions.

“It is very important for families to know that RSV is the leading cause of hospitalization during the first year of life,” he concluded. “In Quebec, we have seen an 85 per cent reduction in the risk of emergency room visits and intensive care admissions (among vaccinated infants).”

The findings of this study were published in the Canadian Medical Association Journal.

–This report by La Presse Canadienne was translated by CityNews