Since 2022, a triple epidemic of respiratory viruses — RSV, influenza and SARS-CoV-2 — has been disrupting our daily lives. In addition, the media constantly reminds us of how this is straining emergency departments. How does the present respiratory virus season differ from seasons during the pre-COVID era? As a specialist in virus-host interaction, I would like to shed some light on the new dynamics of the respiratory virus season.
The infamous SARS-CoV-2
- Despite limited access to screening tests, analysis of the number of hospital admissions shows that the virus is still going strong.
- It has a strikingly efficient capacity to spread through aerosols, especially as we take refuge indoors to escape the cold.
Resurgence of seasonal flu
- After a hiatus due to health measures, the influenza virus, which causes seasonal flu, has returned with the same force.
- It is once again circulating in different variants belonging to Types (strains) A and B, although scientists believe that one Type B strain, the Yamagata lineage, has disappeared.
And what about RSV?
- Bronchiolitis is characterized by the obstruction of the small airways, which can progress to wheezing or respiratory distress.
- But RSV also severely affects the elderly and adults who are immunocompromised or have existing chronic conditions.
- Admittedly, although these three viruses are attracting attention, other less publicized respiratory viruses are also circulating, demonstrating a diverse viral environment.
SARS-CoV-2 has turned everything upside down
- The challenge is amplified by the extremely high transmission capacity of SARS-CoV-2 compared with influenza and RSV, which makes seasonal management much more complex.
- But today, the picture has become even more complex with the continuing presence of SARS-CoV-2.
Beyond infection
- In addition, it causes long-term consequences after infection, such as post-COVID syndrome (also known as long COVID), which affects millions of people.
- The extent of the consequences of infection and reinfection on human health remains uncertain, as does the effectiveness of vaccines in limiting these effects.
The importance of vaccines
- The final distinction from the pre-pandemic period is the arrival of RSV vaccines.
- However, these two vaccines have not yet been officially recommended.
- The trio of vaccines against COVID-19, influenza and RSV will certainly help to reduce the severe symptoms associated with respiratory virus infections in the coming seasons.
Nathalie Grandvaux received research funding from the Canadian Institutes of Health Research (CIHR), the Natural Sciences and Engineering Research Council of Canada (NSERC), the Fonds de recherche du Québec - Santé (FRQS), the Canada Foundation for Innovation (CFI), the Fondation du centre hospitalier de l'Université de Montréal, and the Ministère de l'économie et de l'innovation du Québec.