June 12, 2020 13h12
Six myths about the mask
Detector rumour – Agency Science Press
DETECTOR RUMORS / alternately praised or vilified, the wearing of the mask seems, in recent weeks, having finally won its letters of nobility in the majority of countries that have launched their déconfinement. But the exact content of its effectiveness remains difficult to establish. The Detector of rumors flew over the six myths on the mask.
1) The mask is used to protect oneself ? False
The mask protects first of all the entourage of the person wearing it, rather than the person who wears it. It blocks the majority of the particles that this person emits by coughing and sneezing, but also in speaking or breathing. However, this is where the main mode of transmission of the virus, as recalled in particular the Royal Society in Great Britain or the Centre for disease control (CDC) in the United States.
2) The N95 masks are the most effective ? True
Some masks are better than others. As well, the only ones that block at least 95 % of the particles carried by the droplets that we are projecting are the famous N95 masks, which are equipped with a device for filtration of very small particles. This is why these are the ones that should be used in priority by the nursing staff.
The surgical masks — that meet specific standards depending on the country — are also recognized for their effectiveness, in particular by the american Agency of food and drugs (FDA) and the CDC.
For all that, this is not to say that the wearing of masks other than surgical is unnecessary, but rather that their effectiveness requires a common effort and mutual. As the authors write of a review of the scientific literature prépubliée in April and titled Face Masks Against COVID-19 : An Evidence Review : “If each person wears a mask to reduce the risk that it would be, without knowing it, in the process of infecting someone, then everyone is protected,”.
It has been shown in recent months that people can be contagious even if they do not show symptoms : the existence of these “asymptomatic” has become an additional argument for the wearing of masks, including masks for non-medical, say the authors of Face Masks. Even the sound of a bell in a review of the literature published in early may by the Royal Society, and in a forum of researchers, published at the end of may in Annals of Internal Medicine. It concludes that, although it is not completely sure that the cloth mask is actually protecting the surroundings or even the person wearing it, a profit even if minimal in terms of reducing the transmission community, in a context of a pandemic, is not to be overlooked.
3) Wear a mask secures too ? Rather fake
An argument often advanced by the health authorities, and that may explain their reluctance to recommend the wearing of masks, lies in the difficulty to predict changes in the behaviour of people, once the mask is widespread. The fear is that, animated by a false sense of security, citizens began to ill use the mask or to the neglect of important measures of prevention against the COVID-19, such as social distancing and hand washing. The authors of the review of the scientific literature Face Masks Against COVID-19 : An Evidence Review concluded that it was unlikely that this risk compensation eliminates the benefits brought by the widespread use of the mask.
They recalled that similar concerns had been voiced during the implementation of HIV prevention strategies, when the introduction of laws on crash helmets, on the port of the seat belt in the car or on the subject of helmets in alpine skiing. According to the scientific literature that they have consulted, the implementation of each of these measures would not have led to a resurgence of risky behaviour, but it would have led to an overall greater level of security. The Royal Society advance the same argument in his paper.
(4) The authorities have changed your mind ? Yes and no
At the end of February, Jerome Adams, the federal administrator u.s. public health service, had urged the american people to stop buying masks. A position shared by the Center of disease control (CDC). It was, however, at the beginning of April, changed its guide of recommendations, Americans are being called now to wear the mask where the measures of social distancing may not be met. The leaders of canadian and quebec also started in April and may to show hidden.
However, as suggested by Face Masks Against COVID-19 : An Evidence Review, one of the reasons explaining the reluctance first of several countries has been the fear of running out of stock, particularly in the N95 masks and surgical. Such a situation would have been catastrophic for the health care staff. “The strategies to manage these reserves, critics have been to appeal to the public to reduce its use of masks for medical care,” the authors write.
It is also possible that another argument has played. In the past, the mask was not unanimous and some studies had indeed found that wearing a mask does not protect, in particular, in the case of influenza and the common cold. In comparison, the scientific literature on the coronavirus, which are viruses bigger, is much more recent.
5) We can assess the reduction of risk ? False
On the one hand, the research refers more to the fact that the majority of people contaminated have been by direct exposure to a person who is already contaminated and often without symptoms — therefore, by droplets that this person emits while speaking. On the other hand, we are able to better the percentage of droplets as a mask can block. Therefore, can we put a figure, such as memes, have suggested, on the reduction of risk of transmission of the virus when you wear a mask ?
As argued in the topic of verification of the facts set-top boxes, the search is not made here : the transmission from person to person depends on too many factors, ranging from the place where these two people are to be found (open or closed space, air conditioning, etc) to the time during which these people have been in contact via the viral load of the infected person.
6) This is what has made the difference from one country to the other ? Not clear
Many of the countries that have flattened quickly their “curve” are those where the wearing of the mask is in common use : Japan, Singapore, Hong Kong, South Korea… “Multiple official sources cite it as the reason to this is the implementation of policies of masks, because of the transmission asymptomatic,” writes the Royal Society.
However, these good results cannot be attributed solely to the masks : the fact that these countries have been in the front line during the SARS outbreak in 2003 has made sure that they were already better prepared to put in place policies to severe (mass screening, containment, isolation, etc). South Korea, for example, has a policy of tracking systematic of all the people with whom has been in contact with an infected person, since the transactions of credit cards of this latter up to the GPS data from his phone. “No single factor can explain the differences between nations or regions,” concludes a report recently of The Atlantic.
It should also be noted the case of New Zealand and Iceland : they have flattened their curve quite quickly, without that wearing a mask is not a recommended practice. Conversely, Morocco has imposed the wearing of the mask very soon, but also a policy of containment is very strict. In Europe, the Czech Republic is cited for having imposed very early in the port of the mask and have a number of deaths less than its neighbors.
“When used in conjunction with a generalization of the tests, tracing contacts, quarantine of any person who might be infected, washing hands and distancing physical, the masks are a valuable tool in reducing the transmission of community”, in abundance, for their part, the authors of the literature review Face Masks.
In its guidelines from the beginning of April, the world health Organization (WHO) returns the ball to the leaders, considering that there was not sufficient scientific evidence “to advise or discourage the use of masks (medical or other) by the people in good health within the community”. New Zealand continues not to invite its people to wear the mask, while warning that it will update this recommendation, “in the event of new evidence or guidelines of the WHO, or if we see a change in the evolution of the COVID-19 in New Zealand”, we read on the website of the ministry of health in new zealand. In new guidelines released on 5 June, WHO invites governments to encourage the wearing of the mask in the places “popular” of the “regions most affected” by the pandemic, or when the detachment physics is difficult.