Quebec teams manage to isolate infectious particles of the virus from air samples taken from hospital rooms of patients with COVID-19, and kept frozen for more than a year, according to a new study.
The research work was carried out by the team of Nathalie Grandvauxresearcher at the CHUM Research Center (CRCHUM) and professor at the University of Montreal, in collaboration with the teams of Caroline Duchaine (Laval University) and Yves Longtin (McGill University).
Published in the journal Clinical Microbiology and Infectionl’study thus sheds light on a scientific field that has been little explored since the start of the pandemic: the transmission of the virus by airway.
“In our study, we demonstrate through an experimental model that it is possible to isolate and cultivate infectious viruses from air samples, explains Nathalie Grandvaux. And this, even if they were sampled more than a year ago, frozen and then stored before being cultured. »
If the admission of viral transmission by air has been slow on the part of public health authorities, including the World Health Organization, it is partly due to the lack of scientific data demonstrating the presence of infectious viral particles in aerosols.
“These are difficult studies to carry out, because you have to preserve the infectiousness of the virus during sampling, have the right culturing techniques and have access to a containment laboratory 3 like that of the CRCHUM. »
A unique method
Audray Fortin, research officer in Nathalie Grandvaux’s team, and first author of the study, developed a unique culturing method to be able to amplify the traces of viruses collected by Caroline Duchaine, a Canadian bioaerosol specialist, and her team.
Another scientific tour de force, since the samplers, collection boxes placed in the rooms of people with COVID-19, must be able to acclimatize the virus within them and protect it during storage.
In all, around 30 samples were collected in 10 different rooms from patients with COVID-19, then stored in frozen form in a biobank for 14 months.
Using aerosol samples from one of the patient rooms, the scientific team was able to reveal the presence of viral particles capable of replicating.
“Thanks to our method, it is now possible to retrospectively assess the presence of infectious SARS-CoV-2 in samples taken during the different waves of the pandemic,” says Nathalie Grandvaux. “These data will allow us to better understand the importance of transmission of the virus by air and to put in place appropriate prevention strategies. »
Better prepare for the next pandemic
These learnings could be used to prepare for the next pandemic, whether of SARS-CoV-2 or another respiratory virus.
“Our research should raise awareness of the presence of infectious viruses in the air. They plead for the importance of targeting airborne transmission in individual and collective protection measures, in particular by improving indoor air quality. »
As for the method of collection and culture, it could be adapted to other closed environments than hospitals, such as schools for example, to test the quality of the air and evaluate the effectiveness of the means of protection against transmission. airborne virus.
About the study
L’article « Detection of viable SARS-CoV-2 in retrospective analysis of aerosol samples collected from hospital rooms of patients with COVID-19by Audray Fortin and her colleagues was published online March 22, 2022 in the journal Clinical Microbiology and Infection. Funding for the study was provided by the Fonds de Recherche du Québec-Santé and the Fondation du CHUM.
Written by: Bruno Geoffroy
