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Lightning Fact Check: Denis Rancourt and masks

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A lot of fake news and dubious claims are circulating. But some can be debunked in a few easy steps. A long fact-checking process isn’t always necessary. Through these short answers to our readers, the Rumour Detector’s assistants offer some easy tips everyone can use as a first check. 
The message from our reader Vero (in french)


"But who is Denis Rancourt?"
"COVID-19: masks and “barrier gestures” are useless…" 
"Stop believing stupidly in the official line on Covid and…"


Our answer 

Hello Vero!  

Like you, one of my first reflexes when I saw this video was to ask:  who’s this specialist, Denis Rancourt? Especially since his study seems to say the opposite of the general position scientists are taking. I’ll get back to this.  

But first I asked myself: who is Jérémie Mercier, the presenter of the video. He’s the source of this interview. Clicking on his name at the bottom of the video took me to his YouTube channel’s home page. A glance showed me that several of his videos have sensational titles: “Le grand mensonge” (The big lie), “Le scandale” (The scandal), “L’arnaque” (The sting). His positions don’t seem to have any nuances! Before sharing his videos, I’d try to use reliable sources validate any information from this YouTuber.  

As for Mr. Rancourt, a quick Google search tells us a little more about him. His biography on Wikipedia is also eloquent. He is indeed a recognized scientist, specializing in physics — and not in medicine or epidemiology. But he’s largely known for his confrontations with his employer, the University of Ottawa, and his positions as a climate skeptic. I see a red flag here.  

But his study on mask wearing is what’s important here. A study is always better than an opinion, even if the opinion comes from a scientist.  

I went to the link under the video. It’s presented as a literature review of what’s been published on masks for over 10 years. First of all, it’s a preprint paper. That means the research wasn’t peer reviewed by experts in the field. Secondly, the very first thing he says is; “Masks don’t work” (“Les masques ne fonctionnent pas”). That’s a little surprising, considering all of the literature. We all know that research has established nuances on the effectiveness of masks, depending on the circumstances

People who have more expertise than me in viral transmission and epidemics can dig into his data and analyze it more deeply. But one thing is certain. The virus is a complex subject. Its existence was unknown 6 months ago. A definitive conclusion like Rancourt’s seems premature, based on literature that essentially covers the pre-COVID period. Remember that the arguments on mask wearing have always been nuanced over the past 6 months. There are pros and cons. And it all depends on the places  you go and the people you meet every day. Working in a hospital or a long-term care centre isn’t the same as going to a supermarket. Being with a large group of people in a bar isn’t the same as being in a park. So it seems premature to conclude that everything is “useless”, as the YouTuber writes.  

I note that he immediately adds that we mustn’t believe the “official line” (“discours official”). That’s another argument that seems reductive, because the official line can be sometimes, true, sometimes false.  


- Josée Nadia, assistant to the Rumour Detector  


This article was originally published on the website of L'Agence Science-Presse (French only).


Image by roungroat - Rawpixel 


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