Let us remember at the outset: it is via droplets and direct contact between humans that the new coronavirus is very largely spread. But what about door handles, switches, faucets etc. ?
Since the start of the crisis, global health officials have never displayed any particular concerns about contamination from the objects. Via banknotes? The risk is "very low". Via parcels from China? "Extremely weak".
An American study came to shed some light this week. Virology researchers have tested the resistance of Covid-19 on different surfaces in the laboratory. Conclusion: the virus could survive up to three days on plastic and iron, up to 24 hours on cardboard / paper, and four on steel. As for particles nested in aerosols, they could remain for three hours. In February, the work of English colleagues was more alarmist, and counted on nine days for plastic or five for cardboard.
These results, which have yet to be validated by peers, make researchers say that transmission by air and objects is therefore "plausible". No way to give in to panic, they warn. These estimates are indeed in line with the data collected during the SARS crisis in 2003. At the time, the epidemic was already spreading mainly between humans, and not in the context of "environmental sustainability", c that is to say via external elements.
No evidence of contamination from objects
Furthermore, the persistence of particles does not in any way mean that the latter are still infectious. Presence does not mean contamination. After a few hours, the rate of cell activity, and therefore the risk of infection, would drop even drastically, according to the same study. And that doesn't matter the surface.
As it stands, there are therefore presumptions of indirect contamination but no evidence. In early March, Chinese scientists also made this assumption after investigating a strange cluster where individuals, located on different floors of the same building and never having come into contact, were detected positive at the same period. Their work has been published in the journal Emerging Infectious Diseases.
In the absence of clear alerts, global health authorities therefore focus their prevention strategy on barrier actions and the rules of social distancing. Actions that Edouard Philippe insisted on Saturday evening, when regretting the lack of discipline of the French. As for potentially contaminated surfaces, it is advisable to use bleach. The dosage prescribed by the United States Federal Health Agency (CDC): four teaspoons for one liter of water.
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