At the start of the coronavirus epidemic, we were told that masks were useless. Et puis, finalement, we all had to wear it at the end of the epidemic. At the same time, the general director of health Jérôme Salomon explains to the parliamentary commission of inquiry that’they would not protect… What make us crazy…
So the mask, useful or not useful ? What scientific studies really say ?
UPDATE on the uselessness of masks, proven !
Wearing a mask is presented as one of the flagship measures of social distancing to bend the curve of the coronavirus epidemic. "By wearing a mask, you protect me, and me with my mask, I protect you " : since the first week of deconfinement, des "Covid prevention crews", set up by the City, crisscross the streets of Strasbourg to support the inhabitants, relates a report by France Soir.
This restrictive measure is difficult to observe on a daily basis. It generates a lot of discomfort, and sometimes migraines, as a supermarket cashier told me I asked how she lived wearing the mask… Gold lately, I came across a study debunking the effectiveness of the mask, whether in surgical or FFP2, against influenza-like respiratory conditions.
Could it be that the government was right not to recommend wearing a mask at the start of the epidemic? Today, everyone agrees that masks are effective and that it is partly because of this lack of protection that the virus has done so much damage in France. So many people wear the mask on the street and many stores impose it on customers. What is it really? Apparemment, it's far from obvious.
Meta-analyzes that do not conclude that they are effective
Former professor of physics at the University of Ottawa, Denis Rancourt is currently a volunteer researcher with the Ontario Civil Liberties Association. Concerned about citizen liberties, this researcher looked into studies on the wearing of masks, whether surgical or otherwise. He only selected rigorous studies, namely randomized controlled trials (Randomized controlled trial, RTC).
Luckily, the scientific literature has particularly expanded in recent years on this subject, with meta-analyzes, studies that synthesize the work of other studies. Dont a Chinese meta-analysisand very recent, published in 2020. There are therefore reasons to carefully consider the conclusions of this Canadian researcher. To note that, according to Rancourt, the majority of studies have been carried out in a hospital setting, where this type of respiratory infection invades the corridors.
Denis Rancourt's conclusion is categorical. Wearing a mask gives an "illusion of security". No study shows the benefits of a general mask-wearing policy in public. Not a shadow of benefit to protect yourself from influenza-like respiratory viral infections, not even a slight decrease in risk: no statistically valid difference could be proven ... No superiority of hyperfiltrating masks over surgical masks could also be reported.
You can find this selection of meta-analyzes in the publication of Denis Rancourt: « Masks Don’t Work: A review of science relevant to COVID-19 social policy ». If English puts you off, I would rather recommend this video in French, where he very clearly explains the results on Youtube to Jérémie Mercier: Covid-19 : Masks and “barrier gestures” are useless (Prof. Denis Rancourt)
Note that the original Publication has been put online on the ResearchGate site, then removed by site administrators, for astonishing reasons. Without substantive argument, it is first of all not to contradict the official recommendations and not to discourage the wearing of a mask (see exchanges between the site and this researcher). For the scientific debate, we will iron! The precautionary principle applies while waiting for ResearchGate.
I have reviewed the studies cited by Denis Rancourt and I come to the same conclusions more or less. It still seems that there may be a slight benefit from respirator masks (in a few rare studies) but that supposes a PERFECT use, which is never the case in everyday life. So the benefit turns out to be zero in practice. In any case, no study seems to recommend wearing the mask for the general public…
Why it does not work?
For Denis Rancourt, the mode of virus transmission explains the failure of the masks. As we focus on droplets and other sneezing, the virus would spread much more effectively when it is suspended in the air.
"The main route of transmission is that of airborne particles […] which are too fine to be blocked, and the minimum infectious dose is less than one air particle. "
Even on a surface to which it can hang for a long time, and with whom you may be in manual or oral contact, "The virus is much less transmissible" than in the air we breathe where it circulates and persists as an aerosol.
Wearing a mask is never really perfect in practice: the shape of the face will always allow air to pass which may contain suspended viral particles. Et puis, how to avoid breathing?
And the negative effects of wearing a mask?
Rancourt believes that social distancing measures do no more than mask to slow the epidemic. He also questions the possible harms of wearing a mask: "Can the captured droplets transform into breathable aerosolized particles? Can the mask become a collector of pathogens that the wearer could have avoided breathing if he had not worn a mask? Does the mask contribute to the inhalation of fibers or potentially harmful substances? »
"By making recommendations and imposing the wearing of masks on the general public, or by approving this practice, governments have both ignored scientific evidence and acted against the precautionary principle. (…) Such recklessness is certainly found in the current global confinement of more than a billion people., unprecedented medical and political history experience. "
Humidity would reduce the transmission of the virus ...
Denis Rancourt is also interested in the phenomenon of seasonality. The fact is that no one today understands why epidemics appear, reach a peak then disappear as they came. To understand this mystery, you have to be interested in the work of Shaman (2010) and other researchers who link outbreaks to weather.
"The seasonal structure of excess mortality from respiratory disease can be explained quantitatively on the sole basis of the humidity rate and its direct impact on the transmission of airborne pathogens". When it's very humid, the viral particles which travel in the form of aerosols would be condensed in droplets, much less transmissible, before reaching the ground. The basic reproduction rate of a virus (this R0) would also be strongly or mainly dependent on the ambient humidity. It could therefore vary considerably depending on the climate, weather. Otherwise, the lungs would also be less irritable in wet weather than in dry weather. Our personal resistance too could depend on weather conditions.
Good rain, nothing like chasing viruses? This remains to be demonstrated, but it’s an interesting track to study!
This is what the weather chain did in an article that I recommend to you. I also suggest some links to studies supporting this thesis. To fight against the flu and other winter viruses, get a home air humidifier, to avoid too dry air, is apparently a better investment than buying masks…
Rainfall this winter and March 2020 :
- a rainy winter that may have offset the peak of the usual seasonal epidemic : http://www.meteofrance.fr/climat-passe-et-futur/bilans-climatiques/843/bilan-climatique-de-l-hiver-2019-2020#
- the second part of March, favorable to viruses : https://actualite.lachainemeteo.com/actualite-meteo/2020-04-03/bilan-meteo-de-mars-2020-humide-et-doux-puis-frais-et-sec-54644
 Péculier Cléa, « A Strasbourg, "Covid prevention crews" to encourage people to wear a mask ", FranceEvening, 27.05.2020.
 You can see Denis RANCOURT's profile on the siteResearchgate.
Jérôme Salomon, general manager of health, before the parliamentary committee of inquiry, about masks : https://www.lefigaro.fr/politique/masques-face-aux-deputes-le-pr-salomon-se-justifie-20200616