In the face of the Covid-19 epidemic, vigilance is more essential than ever. Wearing a mask, washing hands, physical distancing … These are all essential barrier gestures to limit the spread of the coronavirus, which is transmitted mainly through droplets of saliva, but also through infected surfaces. But the more the epidemic progresses, the more we learn about the different modes of transmission.
Covid-19: surfaces would not be so contaminating
Many people disinfect doorknobs, stair railings or even supermarket trolleys to prevent contamination from surfaces on which contaminating droplets have been deposited. And for good reason : "the virus is then transmitted to a healthy person who handles these objects, when she puts her hands to her mouth", can we read on the government website.
A recent study published in the journal Nature Yet puts the role of surfaces in the transmission of the coronavirus into perspective. "Covid-19 rarely spreads through surfaces (…) It is not a major source of infection", can we read in these works.
How to explain this phenomenon ? "We know that the surfaces, first of all, there is a spontaneous elimination of the virus which will take place over time, and that the contamination occurs at that time in an indirect mode, (…) it would be necessary an extremely large quantity of virus to be able to create an onset of disease ", indicates to Franceinfo Dr. Benjamin David, infectious disease specialist at Raymond Poincaré Hospital in Garches (Hauts-de-Seine).
A previous study conducted by American researchers from the National Institutes of Health and published on the scientific prepublication site MedRxiv in March, however, it revealed that the coronavirus could survive for several hours, or even several days, on certain surfaces. Its lifespan is thus estimated at 4 hours on copper, up to 24 hours on cardboard and up to 3 days on plastic and steel,
On tissue, the coronavirus could survive for up to two days, according to a study published in May 2020 in the journal The Lancet. "However, just because a little virus survives does not mean that it is enough to infect a person who touches that surface. Indeed, after a few hours, the vast majority of the virus dies and is probably no longer. contagious", nevertheless recalls the Ministry of Health.
Covid-19: saliva droplets, the main vector of contamination
Covid-19 is transmitted mainly via droplets of saliva emitted by an infected person when they cough or sneeze. This is the reason why a gap of one meter between individuals has been advocated since the start of the epidemic. This distance helps prevent large particles, which are particularly contaminating, which, due to their weight, quickly fall to the ground.
Covid-19: possible contamination from the air?
In early October, the U.S. Centers for Disease Prevention and Control (CDC) added the airway as a new mode of transmission for Covid-19. The new guidelines say it is possible to become contaminated after being exposed to small droplets and infected particles that can remain in the air for several minutes or hours. The CDC added that transmission of the virus by air took place mainly "in confined spaces with insufficient ventilation".
A study published in July on scientific prepublication site MedRixv already suggested that the microdroplets emitted when speaking or even breathing remain suspended in the air and can transmit the coronavirus.
Researchers at the University of Nebraska (USA) conducted an experiment with patients who were bedridden in rooms. Speaking, these produced microdroplets which remained suspended in the air for several hours. Scientists took these microdroplets from the air before placing them in culture. The virus "replicates in cell culture and is therefore infectious", found Joshua Santarpia, co-author of the study. However, the authors stress that further research is needed to confirm these results.
Speech, a vector of transmission of Covid-19
Speech is also a vector of transmission for Covid-19. A more or less true phenomenon depending on the language spoken! This is what a study published in the journal reveals Medical Hypotheses and conducted by researchers from the Russian Peoples' Friendship University. The existence of aspirated consonants in certain dialects could thus promote the spread of Covid-19.
To find out, the researchers used official data from 26 countries with more than 1,000 Covid-19 cases as of March 23, 2020. Languages spoken in these countries have been divided into two groups based on the presence or absence of aspirated consonants. Result: the countries which spoke the majority of the languages of the first group had more cases of Covid-19: 255 per 1 million inhabitants, against 206 cases in the second group.
"Although no clear relationship has been observed, we do not rule out that the spread of Covid-19 may be partly due to the presence of aspirated consonants in a country's main language of communication. be a valuable idea for epidemiologists ", Georgios said. Georgiou, lead author of the study.
Covid-19: apply barrier gestures to limit risks
These different modes of transmission underline the importance of barrier gestures. It is therefore advisable to:
- wear a protective mask;
- wash your hands regularly with soap and water, or with hyroalcoholic gel in the absence of a water point;
- cough or sneeze into the crease of his elbow;
- use disposable tissues and throw them away immediately afterwards;
- keep a physical distance of at least one meter, and therefore stop hugs, hugs and handshakes.
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