Social Distancing

Social distancing: British researchers question the distance of 1 meter

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Keeping a distance of one meter between two people is an outdated scientific claim, according to British researchers. In an analysis, they detail why this view of virus transmission is too simplistic.

The fight against Covid-19 is more relevant than ever as a second wave of contamination seems to be arriving.

Washing your hands very frequently, putting on a mask, coughing into your elbow, or keeping a distance of at least one meter between yourself and others are the main barrier gestures that should be observed more than ever to limit the spread of the new SARS coronavirus. -CoV-2.

However, there is one such rule that would be particularly outdated, if British researchers at the University of Oxford are to be believed. In an analysis published Aug. 25 in the British Medical Journal (BMJ), they believe this rule of one or two meters between two people to reduce the spread of the coronavirus is scientifically "out of date", and is based on knowledge related to other viruses. and therefore not specific.

The one meter social distancing is in fact based on the fact that the virus is transmitted through large droplets (or sputum) or slightly smaller droplets present in the air when speaking, sneezing or coughing. For the authors of the analysis, this rule therefore excludes the significant role of exhaled air, which can be loaded with viral particles even if it does not contain large droplets of saliva.

Several scientific papers suggest that Sars-CoV-2 can travel more than two meters when coughing or screaming, and up to seven to eight meters in the air while circulating around an infected person. Furthermore, ventilation and air renewal systems also have a role to play in the spread or not of viral particles.

In other words, decreeing a distance of one meter between two people is too simplistic or even insufficient depending on the circumstances. The viral load of the person emitting the microdroplets, the duration of exposure to exhaled air, whether or not they are wearing a mask, the type of activity they perform and the levels of ventilation are factors that influence viral transmission. and which ones should be considered, say the researchers.

Ideally, it would then be necessary to offer "greater protection in higher-risk contexts, but also greater freedom in low-risk contexts, potentially allowing a return to normalcy in certain aspects of social and economic life," they indicate.

In particular, the researchers developed a table where the risk of contagion is reported in green (low), yellow (medium) and red (high) according to the level of occupation of a place (low or high), whether it is a place outdoors, a well-ventilated interior or a poorly ventilated interior, and depending on the duration of contact with others, whether or not a mask is worn and whether you speak, sing, or remain silent.

Thus, in a poorly ventilated and heavily trafficked place, we almost always run a high risk of being contaminated by an affected individual, regardless of whether we speak or not, while we are in a place with few people and in the open air, the risk is almost always weak.

The authors of the analysis believe that physical distancing is part of a set of health measures aimed at curbing the Covid-19 epidemic: hand washing, surface cleaning, air sanitation, use of protective equipment such as masks, isolation of infected people, etc. In short, physical distancing alone is largely insufficient in certain circumstances, while it can be exaggerated in other cases.

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