The infant without a comorbidity
In the fall of 2024, Ontario and Quebec introduced publicly funded universal programmes offering nirsevimab free to all infants. Health Canada authorized that long-acting monoclonal antibody in 2023 for prevention of RSV lower-respiratory disease in newborns and infants in their first RSV season.[1]
Stephen Freedman says most infants with RSV infection were otherwise healthy children. Only 3 per cent of infants who tested positive for RSV had a comorbidity.[1]
An offer without a filter
Up to 2 per cent of infants born in Canada are hospitalized with RSV each year. A programme that tries to guess a marked minority can miss the healthy majority who still fill the wards. Ontario and Quebec lifted that filter.[1]
Access is the mechanism here: the antibody is available in the first RSV season without a comorbidity filter. For provinces that have not yet opened the same offer, the next RSV season is the observation of whether a filtered invitation leaves out infants outside that 3 per cent comorbidity share.[1]