Are there similarities between the Sars-Cov-2 virus (responsible for Covid-19) and the influenza virus?
Dr. Sylvie Behillil. Yes. The influenza virus and Sars-Cov-2 are both viruses that cause respiratory infections. These are so-called “RNA” viruses, one of the properties of which is to mutate (during replication), that is to say to modify themselves. If Sars-Cov-2 has not mutated much since the start of the epidemic, influenza viruses evolve regularly from a genetic point of view.
The influenza virus and Sars-Cov-2 also have the same mode of transmission: via droplets of saliva (projected when we speak, when we cough, when we sneeze …) and via the intermediary hands (a person sneezes on the metro bar, someone arrives, touches the bar then touches their mouth and / or nose …).
What about the symptoms? Can we compare those of Covid-19 to flu syndrome?
Dr. Sylvie Behillil. At the onset of Sars-Cov-2 infection, it is difficult to tell the difference between influenza and Covid-19. The two pathologies can thus cause respiratory symptoms (cough, in particular), fever, headache, myalgia (muscle pain), arthralgia (joint pain), even digestive disorders (nausea, vomiting, transit problems). But, in the case of Covid-19, we can also observe the appearance of more specific symptoms such as anosmia (loss of smell) or ageusia (loss of taste).
In addition, in a second step (around the 7th – 10th day after infection), patients suffering from Covid-19 may see their condition worsen with cardiac, vascular or even renal manifestations – such as a stroke. (Stroke) or pulmonary embolism. These complications result from the cytokine storm, that is, the runaway immune system that can follow the viral infection with Sars-Cov-2. This is a phenomenon that is not observed with the flu.
The flu is responsible for between 9,000 and 15,000 deaths each year in France while the Covid-19 has caused “only” 32,500 deaths to date: why are doctors so worried about the epidemic coronavirus?
Dr. Sylvie Behillil. What must be understood is that the influenza virus is well known today. There is a vaccine (which is safe and provides immunity for 6 months to 1 year) and an antiviral drug (Tamiflu®). In addition, while influenza is indeed a fatal disease (although around 2,000 deaths could be avoided if all frail people were vaccinated), it is seasonal: in December, hospitals are ready to take care of patients. affected by influenza during this epidemic which traditionally lasts between 5 and 12 weeks.
Conversely, the Sars-Cov-2 virus is still poorly understood – we discover things about it almost every day. The epidemic (which started at the end of 2019 in Asia) has already gone through 3 seasons: if it seemed to weaken this summer, the figures show that it is probably on the rise. It affects the whole world.
Admittedly, 80% of Covid-19 cases are mild: however, we do not yet know all the possible complications of the disease, and we do not yet have a precise list of the people most vulnerable to Sars-Cov- 2. Some patients with Covid-19 have spent more than 3 months in intensive care: this is a situation that is not observed in the event of the flu.
Faced with this new coronavirus, caution remains in order: barrier gestures are more essential than ever!
Thanks to Dr. Sylvie Behillil, deputy head of the CNR for respiratory infection viruses at the Institut Pasteur.
Don’t forget: from October 7 to 11, 2020, you have the opportunity to help fund research at the Institut Pasteur on the occasion of the 14th edition of the Pasteurdon. You can make a donation on the pasteurdon.fr site, at 36 20 say “Pasteurdon” (free service + call price), by check payable to Pasteurdon (to be sent to 25 rue du Dr Roux, 75015 Paris), by SMS by sending “DONATION” to 92 112 to donate 20 €.
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