Do masks prevent sickness? A coronavirus guide on what to do (and not do) to stay healthy

Bottom line: Wash your hands. Stop touching your face. Avoid large crowds if you are high risk. And leave the masks to the health care workers.
Image: Medical Masks
People wear medical masks on the AirTrain en route to John F. Kennedy Airport on Saturday, March 7, 2020, as concern over the new coronavirus grows in New York City.Spencer Platt / Getty Images
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By Leora Horwitz, associate professor of population health and medicine at NYU Langone Health

My parents are confused and worried, and I can't blame them. Every article they read and every TV segment they watch about the novel coronavirus outbreak is dominated by pictures of people in masks. Hundreds of people at a time, all in masks. But then the surgeon general says to stop buying masks, the Centers for Disease Control and Prevention says healthy people shouldn't wear masks, and even former President Barack Obama says to leave the masks to the health care professionals. What gives?

To understand what's going on, you need to understand first how you get infected with the new coronavirus. The virus spreads when infected people cough or sneeze, releasing tiny droplets of saliva into the air. These droplets contain virus particles, which then spread through the environment. You get it when it gets into your eyes, your nose or your mouth. So it seems pretty obvious that a mask should stop those saliva droplets from getting into your face, right? Well, not so fast.

Those droplets are heavy. They don't go very far, probably not more than 6 feet. That means you need to be standing right near someone coughing into your face to get infected directly by the droplets. If you live in the same household as someone who has been diagnosed with COVID-19, the disease caused by the virus, that's a real risk. If you're a health care worker taking care of someone who has been diagnosed, that's also a real risk. In those cases, wearing a surgical mask for prevention is a good idea (along with eye protection for health care workers).

But if you're just going about your daily business? Really unlikely. Right now, even if the U.S.has tens of thousands of undiagnosed cases, that would still mean fewer than 1 in 1,000 people have active disease. That's why every public health official and organization has been saying there is no need to wear a mask if you're a healthy, uninfected person.

It's much more likely that you would get the disease through your hands. You shake the hand of someone infected or touch something that person has contaminated with the virus, then you touch your eyes, mouth or nose, and voilà, you can become infected. That explains why, along with telling you not to bother with the masks, the same public health officials and agencies are shouting at you to wash your hands and stop touching your face.

What are masks good for, then? First, they are crucial for people who have the disease. Remember those drops of saliva? Wearing a mask if you're sick can help catch a large number of them, greatly reducing the amount of virus that gets into the environment or onto other people. Second, they help health care workers, who are constantly in close contact with lots of sick people coughing in their faces, to avoid infection. Third, they may help you avoid infection if you live with someone who has the disease or, perhaps, if you live in an area with a very high rate of disease in the community, as long as you are careful not to touch your face more because of it.

But there's a catch. There are actually two main types of masks: surgical masks and N95 respirators. Surgical masks are what you see in all the pictures. They are what are useful to prevent infection if you are sick. Should you have some regular surgical masks in the house? Maybe a handful, to wear if you get sick. You don't need a hoard of them.

But what about the other kind: N95 respirators? They keep out even smaller particles. Aren't those even better? No. No ordinary person will ever have any need for N95 respirators for the coronavirus. Not if you are healthy. Not if you are sick. Not ever.

Why not? First off, they aren't designed for diseases like COVID-19. An N95 respirator is designed for airborne diseases that travel not on drops of saliva but on tiny particles in the air. There aren't many of those. Tuberculosis. Measles. Chickenpox. Not the coronavirus disease. A regular surgical mask keeps out droplets just fine.

Second, they are no better than a regular, cheaper surgical mask if not fitted correctly. N95 respirators are designed to form an airtight seal around the face to prevent even a tiny bit of air from coming in without being filtered. That's why they come in different sizes and shapes to fit different faces. In fact, they are so hard to wear properly that every health care worker has to undergo specialized, standardized "fit testing" every single year. It's an exhaustive process involving a large plastic hood and copious amounts of aspartame sprayed at your face over and over while you move your head up, down and around, bend and straighten and read a paragraph out loud. If you taste the aspartame, you know the mask doesn't fit correctly.

You aren't going to undergo this testing, and it's quite likely, therefore, that if you buy an N95 respirator, it won't fit you. Plus, you're likely going to contaminate yourself taking it off or to touch your face more than usual, because they are irritating to wear.

Ordinarily, I'd say if you want to waste your money, feel free. But these aren't ordinary times. Because of a combination of decreased supply and massively surging demand, we now have a global shortage of N95 respirators. Global production has been greatly reduced because China is a major mask manufacturer. As of mid-February, China was able to make 15 million surgical masks per day but only 200,000 N95s per day. The U.S. government estimates that we may need up to 300 million N95s in case of a major outbreak.

A global shortage of N95s is bad news for health care workers. First, we'd all really much prefer not to get tuberculosis or measles. Second, given the greatly increased risk to health care workers caring for coronavirus patients in close proximity for many hours, especially during medical situations that cause huge outflux of virus, like intubation, current guidance is that health care workers caring for patients with the new coronavirus should wear N95 respirators.

That may be overkill, but one of the biggest risks of a coronavirus pandemic is a shortage of health care workers. So for now, our plan is to use N95s if we can get them. Every hospital is rationing and conserving. It would help if the general public weren't also buying and hoarding N95s that they will never have a good use for.

Bottom line: Wash your hands. Stop touching your face. Avoid large crowds if you are high risk. And leave the masks to the health care workers.

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