Are Face Masks Effective? CBS News Explains What We Know

Are face masks effective in stopping virus transmissions? CBS News re-visited the question Sunday on its news show 60 Minutes by sending their chief medical correspondent to interview Linsey Marr, a professor who specializes in aerosol science at Virginia Tech University.
Here's a transcript from an excerpt posted on YouTube:

60 Minutes: Is there any doubt in your mind that masks prevent the person who's wearing it from getting Covid — or at least, are helpful?

Professor Marr: I would say they are very helpful in reducing the chances that the person will get Covid. Because it's reducing the amount of virus that you would inhale from the air around you.

It's not going to guarantee that it's going to protect you, because are masks are not 100% effective — we talk about N-95's being 95% efficient at filtering out particles, if they're properly fitted and everything, and so that's in an ideal world. But even so, if you — instead of breathing in 100 virsues, I'm breathing in 20, because my mask was 80% effective? That's a huge reduction, and that greatly reduces the chance that I'm going to become infected.

On the CBS News web site, they highlight this excerpt from the interview:
Early in the pandemic, some guidance from health professionals suggested that wearing a mask might actually lead to infection: A person might encounter a contaminated mask and then touch their eyes, nose, or mouth. But research in the ensuing years has shown that fear to be misplaced. 'There wasn't any evidence really that that happens,' Marr said.

Marr said her team aerosolized the coronavirus, pulled it through a mask, and then examined how much virus survived on the mask. The study reported some viral particle remained on some cloth masks, but no virus survived on the N95s or surgical masks. Marr's team also touched artificial skin to masks and looked at how many virus particles transferred to the artificial skin. No infectious virus transferred.
'I hope the study kind of shows that it's something we don't need to worry about as much as we were told,' Marr said.

CBS gave their video interview the headline 'Face mask effectiveness: What we know now' — and asked professor Marr for a definitive answer:

60 Minutes: There was a lot of controversy over whether or not masks worked at all. Were you able to show that they worked scientifically?

Professor Marr: We were able to show that they block particles that are the same size as those that carry the virus... What happens is the virus is being carried in the air, and it's not just going straight through those holes. It has to weave around all these layers of fibers in there. As the air is going around the curves, the virus may crash into one of those fibers, and so then it's trapped, or maybe it comes up close to the fiber and brushes against it. And the really small particles, like the virus by itself if it were by itself, would be small enough that it undergoes these random motions, because it's getting bounced around by the gas molecules, and it ends up crashing into the fibers of the mask too.

So there was accumulating evidence — and there had been kind of a handful of papers before that, too, showing the same thing. That masks — even cloth masks — do something.

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