(Ottawa) Health Canada has approved a new drug to help protect babies from serious illness caused by respiratory syncytial virus, or RSV.

Nirsevimab, also known by its brand name Beyfortus, was approved on April 19. It was created by AstraZeneca and Sanofi.

Nirsevimab is “a monoclonal antibody aimed at preventing serious lower respiratory tract disease caused by respiratory syncytial virus (RSV) in newborns and infants,” Health Canada spokesperson Mark Johnson said Friday. in an email to The Canadian Press.

The drug, which is given by injection, is also authorized for children under two if they are at risk of serious infection, he points out.

Monoclonal antibodies are made in a lab to mimic natural antibodies to prevent or treat disease.

According to the European Medicines Agency, a regulatory body that last fall approved the drug for use in the European Union (EU), nirsevimab attaches to a protein on the surface of the virus and interferes with its ability to enter the body’s cells, especially the lungs.

Canada already offers the monoclonal antibody palivizumab — also known by the brand name Synagis — to premature babies because they are more vulnerable to serious illnesses caused by RSV. The National Advisory Committee on Immunization (NACI) does not recommend palivizumab for healthy babies.

Palivizumab needs to be injected about once a month—up to four times—during RSV season to remain effective. Nirsevimab only requires a single dose that lasts the entire RSV season.

“It’s a game-changer,” said Dr. Anna Banerji, a pediatric infectious disease specialist at the University of Toronto’s Dalla Lana School of Public Health.

Inuit babies in Nunavut are particularly affected by RSV, says Dr. Banerji.

Although Health Canada has authorized nirsevimab for all infants, it is not known if it will be given massively.

It is up to the provinces and territories to determine who receives the injections, often based on recommendations from the Canadian Agency for Drugs and Technologies in Health (CADTH).

Health Canada has stated that pending CADTH recommendations, it expects nirsevimab “to be available for limited use during the 2023/2024 fall-winter respiratory season.”

Most children in Canada are infected with RSV before the age of two, according to the Public Health Agency of Canada website. It usually causes mild illness, but can be severe and is a common cause of bronchiolitis and pneumonia, the agency says.

Last fall and winter, RSV, along with influenza and COVID-19, led to an increase in pediatric hospitalizations. Infectious disease experts say this is partly due to the lifting of pandemic restrictions, which had prevented respiratory infections in previous years, so children were exposed to RSV for the first time.