A new antibody drug, Nirsevimab, has been approved by Health Canada to protect babies from severe illness caused by respiratory syncytial virus (RSV). The drug, which was authorized on April 19, was developed by AstraZeneca and Sanofi.
Nirsevimab is a monoclonal antibody designed to prevent serious lower respiratory tract diseases caused by RSV infection in newborns and infants during their first RSV season. The drug can be administered by injection and is authorized for children up to two years of age if they are at risk of serious infection.
Monoclonal antibodies are made in a laboratory to mimic natural antibodies to prevent or treat diseases. Nirsevimab works by attaching to a protein on the surface of the virus and hindering its ability to enter the body’s cells, particularly those in the lungs.
Canada already offers another monoclonal antibody, palivizumab, to premature babies because they are more vulnerable to serious illness from RSV. However, palivizumab requires multiple injections during the RSV season to remain effective. Nirsevimab requires only one dose, making it a game-changer, according to 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 vulnerable to RSV, and many become seriously ill each year, requiring transfer to hospitals in the south. A one-dose drug like Nirsevimab could prevent many of these cases from occurring, said Banerji. Although Health Canada has authorized Nirsevimab for all infants, it is up to the provinces and territories to determine who receives the injections, based on recommendations from the Canadian Agency for Drugs and Technologies in Health.
Pending the agency’s recommendations, Nirsevimab is expected to be available for limited use during the 2023/2024 fall/winter respiratory season. Banerji emphasizes the importance of offering Nirsevimab to all Inuit infants in Nunavut, not just those who were born prematurely, due to their heightened risk and limited access to care if they become seriously ill.
In Canada, RSV infection is common, and most children are infected by the age of two. It usually causes mild illness, but it can be serious and is a common cause of bronchiolitis and pneumonia. The drug comes at a time when RSV, along with influenza and COVID-19, caused a surge in pediatric hospitalizations last fall and winter, as pandemic restrictions were lifted, exposing children to RSV for the first time.