Are masks effective?

Are masks effective?

Joe Rogan interviewed American infectious disease epidemiologist Michael T. Osterholm, regents professor, and director of the Center for Infectious Disease Research and Policy at the University of Minnesota, and asked him about the effectiveness of hand sanitiser and masks. Here's the main part of his answer:

Michael Osterholm: (43:20)
The hand sanitisers actually are a great thing for stopping a lot of infectious diseases. They actually are really good. They’re good for your hands, in terms of the skin. They kill the bad bugs. The whole issue of using your hands, touching your face that people all concentrate on, the data’s actually very weak that this kind of virus is going to be transmitted that way. I wouldn’t tell you to stop using hand sanitiser, but don’t think it’s going to have a big impact on this bug....
Joe Rogan: (44:00)
Well, why is [the US health adviser] telling people not to touch their faces?
Michael Osterholm: (44:02)
Because the thought was is that there are receptors around your eye right here that actually for this virus could get in and then get into your body. The data we have on this [bug] is too sparse to say that that’s the case. I think the primary thing about hand washing is legitimate....
    One of the things, people want to do something. They want to feel like they’re doing something, and so we tell them, “Wash your hands often to prevent this disease.” I feel like we’re not being really honest with the people. That the data [for this bug], and we’ve looked at this very carefully, really is about just breathing air, and that’s a hard thing to stop. Keep doing the hand washing, but don’t think that that’s going to stop the disease. You asked about the masks-
    Well, there’s two kinds. Basically, the surgical mask, which just fits over. The reason it’s called a surgical mask is because it’s loose fitting, just fits, kind of ties behind you. It was worn by surgeons so that they don’t cough or drip into your wound. It was never made to protect you from bugs coming in, so those little spaces on the sides: that’s not a problem if I’m breathing into the cloth right in front of my nose, but in terms of the air coming in on the side, they’re not effective at all. People wear them, they look like they’re doing something, they’re not.
    Now, if you are sick, they may help a little bit from you transmitting because if you cough, then you cough right into that cloth, and some of it will embed in there and not get out around.
    The other one though is called an N95 respirator, but for all intents and purposes it looks like a mask. It’s just tight face- fitting and it has a seal at the nose, et cetera.... we use them in healthcare all the time, all the time. They use them, actually, about 90% of them are used in industry, so when they’re grinding things or asbestos, et cetera, they don’t breathe in all these parts.
Joe Rogan: (45:55)
If we have one of those, that’ll do something.
Michael Osterholm: (45:57)
They’re very effective, they’re very effective. The problem is, we have a big shortage. Right now, we have hospitals that are down to just a couple days worth of these masks, the respirators. It’s because we don’t stockpile anything in this country. Hospitals don’t have the money to do that...

[Transcript of whole interview is here. Numbers refer to minutes into the interview, if you prefer to listen to it.]

In short: 

As infection specialist Eli Perencevich, MD, a professor of medicine and epidemiology at the University of Iowa’s College of Medicine, told Forbes, the vast majority of people should not wear a face mask, even if there are cases of the coronavirus in their communities.... “The one time you would want a mask is if you’re sick and you have to leave the house,” Dr. Perencevich told Forbes. “If you have the flu or think you have COVID, that’s when you’d put on a mask to protect others. In your house, if you feel like you’re sick, you should wear a mask to protect your family members.”

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