RSV virions, colorized blue, and anti-RSV antibodies, colorized yellow, shedding from the surface of human lung cells in an electron microscope image from the U.S. National Institutes of Health. Quebec was the first province to announce a publicly funded nirsevimab program for the 2024-25 RSV season.The Associated Press
Quebec’s universal respiratory syncytial virus immunization program proved more than 85 per cent effective in reducing infant hospitalizations, emergency-room consultations and intensive-care admissions, according to a new study.
The province was the first in Canada to announce a publicly funded nirsevimab program for the 2024-25 RSV season. Ontario, Nunavut, Yukon and the Northwest Territories later followed suit.
Nirsevimab, a single-dose antibody injection that provides passive immunity – where a person receives antibodies to a disease rather than producing them through their own immune system – was given to newborns and infants.
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Until nirsevimab was approved in 2023, palivizumab was the only product approved to reduce the risk of severe RSV disease. Canada’s National Advisory Committee on Immunization has recommended nirsevimab over palivizumab, a short-acting antibody that requires monthly injections.
The Quebec study, which was released late last month as a preprint but must still undergo peer review, concluded that nirsevimab was “highly effective.” Its authors estimate that more than half of RSV hospitalizations and ICU admissions were prevented – a figure that could grow to three-quarters with additional immunization coverage.
Jesse Papenburg, one of the study’s authors and a pediatric infectious-disease specialist at the Montreal Children’s Hospital, said the analysis is one of, if not the first, to compare the effectiveness of nirsevimab among healthy and at-risk infants. The authors found the benefit was similar for both groups.
“Assuming that the previous year’s trends would have occurred again in 2024-25, there was over 1,000 RSV hospitalizations that were averted and over 100 RSV ICU admissions,” Dr. Papenburg said. “That’s a lot of pressure on the health care system that this analysis shows was likely averted by the immunization program.”
He said the data are reassuring and compelling for parents who want to better protect their children and should be considered by other provinces and territories that do not currently offer a similar RSV program.
RSV, a highly contagious virus that can lead to complications such as bronchiolitis and pneumonia, is the leading cause of hospitalization for children under the age of one in Canada.
Nirsevimab, sold under the brand name Beyfortus, was approved for use in Canada two years ago and, last May, was recommended by the NACI to protect infants.
Its cost and availability had been a barrier to universal adoption in parts of the country, such as British Columbia, Manitoba and Saskatchewan. These western provinces maintained their then-existing programs last fall, offering palivizumab only to high-risk infants. Since then, many provinces have made changes.
The Globe and Mail reached out to all provinces and territories for an update on their RSV prophylaxis programs.
Manitoba remains an outlier and said it will be sticking to its existing palivizumab program.
Meanwhile, the Saskatchewan government, in May, announced that all infants born one month before or during RSV season will be offered nirsevimab. Prince Edward Island, too, plans to offer a universal program for the coming season.
In B.C., nirsevimab will be offered to high- and moderate-risk infants under two years old. This includes children born prematurely or with chronic medical conditions, and babies entering their first RSV season who live in remote communities or in congregate living settings.
Similarly, in Alberta and New Brunswick, while nirsevimab will not be universally offered, it will be available to high-risk infants.
Maddison McKee, press secretary for Alberta Minister of Primary and Preventative Health Services Adriana LaGrange, said a cost-effectiveness and feasibility analysis is under way to inform decisions for the 2026-27 season.
“While RSV can cause serious illness in specific high-risk groups, it results in fewer severe outcomes at the general population level. This is an important consideration when evaluating broader immunization programs,” Ms. McKee said.
The Ontario government said its universal nirsevimab program has had similar results to Quebec’s.
Ema Popovic, press secretary for Ontario Health Minister Sylvia Jones, said in a statement that the province has seen a “significant decrease” in the rate of infant RSV hospitalizations relative to adult RSV hospitalizations when compared with previous years.
“Beyfortus has been shown to reduce RSV-related hospital admissions by between 81 to 83 per cent,” Ms. Popovic said.
The governments of Nunavut and Newfoundland and Labrador did not respond to requests for comment.
