Health Canada approves RSV vaccine for maternal immunization
Single-shot dose approved for third trimester of pregnancy, Canadians aged 60+
Health Canada has approved a new vaccine geared toward protecting two groups most severely affected by the respiratory syncytial virus (RSV): newborns, who would receive antibodies through maternal immunization, and Canadians over 60.
Pfizer Canada's bivalent vaccine, called Abrysvo, aims to prevent lower respiratory tract disease caused by the virus.
It is the first RSV vaccine in Canada approved for use in pregnancy to provide protection for infants from birth to six months of age, and the second approved for seniors aged 60 and over.
The U.S. Food and Drug Administration approved the vaccine for those same two groups in 2023.
RSV is a common but highly contagious respiratory virus that typically causes cold-like symptoms. For more vulnerable populations — including infants, older adults or those with respiratory or cardiac conditions — RSV can lead to more severe illness, such as bronchiolitis or pneumonia, and potential hospitalization.
A one-shot dose of the Pfizer vaccine given to pregnant individuals during the third trimester (from 32 through 36 weeks) would produce antibodies that pass from parent to the infant. Immunization during pregnancy is already recommended for other diseases, including COVID-19, influenza and pertussis.
For older adults, the dose is also a single shot.
Last August, Health Canada approved another RSV vaccine for seniors from manufacturer GSK. In spring 2023, the agency approved an antibody drug called nirsevimab to help protect newborns and infants from severe illness from RSV.
RSV is a leading cause of hospitalization in infants and young children.
"The first time that an infant encounters RSV and they have no prior immunity to the virus at all, that's when the virus has the greatest chance of getting from the upper respiratory tract and down into the lungs," explained Dr. Jesse Papenburg, a pediatric infectious diseases specialist at the Montreal Children's Hospital.
"When they have a lung infection, it's difficult for them to have to deal with those secretions in the lungs. They may require help in terms of oxygen support, ventilatory support or IV hydration because they're having such a hard time breathing that they wind up not even being able to drink."
The availability of a vaccine given during pregnancy, as well as an antibody drug that can be given to newborns and infants, potentially could "substantially reduce the burden of RSV in Canadian children," he noted.
Consideration of availability, accessibility
According to Health Canada, federal officials will now work with provincial and territorial counterparts to determine interest, potential demand and timelines of introducing these products into RSV vaccination programs.
"We're looking at the winter of 2024-25. That's when I would expect to see one or both of these products being available for use in Canada," Papenburg said.
Key factors include availability — nirsevimab, for example, was approved in Canada in 2023 but there was none available due to extremely high demand in the U.S., Papenburg said — and whether the products will be accessible to every Canadian who wants them.
"I'm a big proponent of universal vaccination programs, but we still can't neglect the cost of these universal vaccination programs on our health-care system. So these economic analyses are important to help us better decide how to use our health-care dollars," he said.
Amid the current cold and flu season, rising cases of RSV, influenza, COVID-19 and other viruses have put intense pressure on emergency rooms across the country.
The introduction of new tools to fight RSV can't come soon enough, according Dr. Fatima Kakkar, a pediatric infectious diseases specialist and clinician-researcher at Sainte-Justine University Health Center in Montreal.
"They should be absolutely widely available. I think the provincial committees have a job to sort of make the official recommendations and encourage people and set up the optimal timing," she said.
"We can't really delay one or two years."
A spokesperson for Pfizer Canada said the company is assessing the availability of its RSV vaccine, consulting with different stakeholders regarding cost and on how to bring it to Canadians "as quickly as possible."
With files from Lauren Pelley and Marcy Cuttler
