Montreal study exposes healthy volunteers to influenza in hopes of advancing vaccine research
Posted September 15, 2026 11:17 am.
For the first time in Canadian history, volunteers involved in vaccine research in Montreal and Halifax will deliberately be infected with the flu in the name of science.
The study began in June. Unlike conventional vaccine trials, researchers will expose carefully screened healthy volunteers to a precisely measured dose of a well-characterized influenza virus in a controlled clinical setting, rather than waiting for participants to become naturally infected.
Researchers say the study uses a type of research known as a Controlled Human Infection Model (CHIM), which allows them to closely monitor participants to determine who becomes infected, how much virus they shed and how their immune systems respond.
The first eight participants have completed the initial stage of the study in Halifax, while the first two participants have now begun the study in Montreal.
“Conventional vaccine development ultimately relies on large field efficacy trials in which researchers wait for participants to be naturally exposed to the virus. Those trials can be lengthy and expensive,” explains co-principal investigator Dr. Brian Ward, Senior Scientist at The Institute, Professor of Medicine at McGill University and Director of the MUHC Vaccine Study Centre. “With this study, we will be able to learn in days what is difficult to observe in a field trial.”
How the study works
Researchers will start with a lower dose of the influenza virus, with participants receiving either the virus or a saline placebo. An independent Data and Safety Monitoring Board reviews the safety data before researchers move to a higher dose.
In groups of four, three participants receive the virus through the nose while one receives the placebo. Participants remain in individual negative-pressure rooms for at least seven days, where they are closely monitored by health-care professionals and can receive antiviral medication if needed.
At the higher dose, researchers expect about 60 to 70 per cent of participants exposed to the virus to develop mild-to-moderate influenza illness. Participants must test negative for influenza by nasal-swab PCR on two consecutive days before they can leave the unit.
The study involves healthy adults between 18 and 45 years old who are not considered at increased risk of severe influenza and who have provided informed consent.
Officials say the goal is not to test a specific vaccine, but to establish the influenza infection model itself. Researchers hope to identify a dose that reliably produces mild-to-moderate illness while collecting safety, virological and immune-response data that could be used in future vaccine studies.
“Developing this specialized expertise domestically using a seasonal influenza virus could eventually allow Canadian researchers to produce new challenge strains more rapidly—including strains relevant to an emerging seasonal or pandemic threat,” says co-principal investigator Dr. Scott Halperin, Professor of Pediatrics, Microbiology and Immunology at Dalhousie University and Director of the CCfV.
Researchers also hope the study will help Canada develop the capacity to manufacture GMP-grade challenge viruses domestically, reducing reliance on viruses produced outside the country.
Before the study began, it underwent independent scientific and ethical review before participants were enrolled.
The study is being conducted at the Canadian Center for Vaccinology (CCfV), a collaboration of IWK Health, Nova Scotia Health and Dalhousie University in Halifax, and at the Centre for Innovative Medicine (CIM) of the Research Institute of the McGill University Health Centre (The Institute) in Montreal.
