When there is a cough or a scream, recent systematic reviews have shown that respiratory drops can travel more than one to two meters. In one study, a few drops were spread eight meters (26 ft) away, leaving a violent breath of air in seconds.
A rule of one or two meters may very well suffice in some situations, but scientists in the United Kingdom say that we need a more subtle model.
Right now, they explain, rules we do not take into account such as ventilation, micro-time, time spent together, indoor or outdoor settings, mask use, or types of social activity – all of which can affect the spread . Coronavirus.
What’s more, the elimination rules often do not consider the size of the air droplets, how much virus the droplets can carry, or how others may be susceptible to these viral loads.
Nevertheless, most regulations for this epidemic fall between one and two meters, and the UK has recently decreased by one meter or more.
Critics of drastic measures say that we are being very cautious, and while this is probably true in some situations, in other cases, scientists argue that we are probably not being sufficiently careful.
The authors of the new analysis write, “Instead of single, fixed physical distance rules, we propose graded recommendations that better reflect multiple factors to determine risk.”
“This would provide greater protection in the highest risk settings, but greater independence in low risk settings, possibly enabling a return to normality in certain aspects of social and economic life.”
The review connects with several other recent criticisms of current social distribution rules. In July, hundreds of scientists wrote a comment from the World Health Organization (WHO) to “reconsider the advice to maintain a distance of at least one meter (three feet) between yourself and others.”
“WHO says there is insufficient evidence to prove the aerosol / airborne transmission of SARS-CoV-2,” one of the authors of the comment explained.
“We are arguing that there is insufficient evidence that aerosol / airborne transmission does not occur.”
The extent to which this occurs is another matter, but there is growing evidence that coronaiores are aerial, even in small droplets, so new analysis from the UK takes a similar prudential approach.
Some recent reviews have found that the risk of getting infected with COVID-19 within a meter is about 13 percent, while beyond a meter, it is only 3 percent.
Nevertheless, the author of this new analysis says that the estimates are flawed and often based on old science, some of which go back to the 1930s. All those decades ago, we predicted how far respiratory droplets could fly when a human cough or sneeze. Yet that simple model does not examine viral loads, droplets of different sizes that can travel over a range of distances, or the type of virus itself.
For example, without exhaled airflow, large droplets appear to travel a maximum of two meters, while smaller ones die very quickly to pull and evaporate. On the other hand with the drift of the wind, clouds of small droplets have been shown to travel beyond two meters.
A study at a hospital in Wuhan, China, found that traces of coronovirus were hanging in the air about four meters away from patients.
Some infectious disease specialists are not too concerned about this, as small doses of aerial coronovirus may not pose a significant risk of infection.
A systematic review of social distancing measures commissioned by the WHO found that a meter or more separation could reduce transmission risk by about 10 percent. Yet scientists in Britain argue that those data are largely based on other coronaviruses, and only partially account for environmental conditions.
While it is difficult to bring individual infections back to their exact source and the distance the person was, there is reason to suspect respiratory drops that may play a role in the current spread of the epidemic – at least in some situations.
In meat packing plants, for example, the outbreak has been particularly bad, and the authors state that it is likely due to high levels of worker fingering, poor ventilation, cramped conditions, background noise (hence, screaming), and wearing sufficient masks. Is not.
He said the same kind of situations can be expected in a pub or live music venue. We have already seen cluster outbreaks in gyms, call centers and churches, where people talk, pant or sing loudly.
In a choir practice in the United States, a symptomatic person was actually found to have infected at least 32 other singers, and possibly 20 more cases had to be confirmed, even though the choir was socially disturbed Was.
These documented outbreaks require clarification, the authors argue, otherwise they will simply occur.
Even after restaurants and bars reopen, countries such as the UK are still asking people to stay at least one meter away, and this may mislead the public, making people actually at risk. Feel safer than being in a situation.
“Physical disturbances should be viewed as only part of a broader public health approach that includes the COVID-19 epidemic,” the new analysis concludes.
“It should be used in combination with other strategies to reduce transmission risk, including hand washing, regular surface cleaning, protective equipment and face covering where appropriate, air hygiene strategies, and isolating affected individuals. To do.”
The study was published in BMJ.