Coronavirus FAQs: Are 3 masks better than 1? Will mouthwash keep you safe?

Each week, we answer frequently asked questions about life during the coronavirus crisis. If you have a question you'd like us to consider for a future post, email us at goatsandsoda@npr.org with the subject line: "Weekly Coronavirus Questions."

Does wearing more than one mask at a time make you safer?

You might have wondered that too if you were watching Monday Night Football last month and saw New England Patriots coach Bill Belichick wearing two masks after his quarterback Cam Newton tested positive for COVID-19.

Well, let's think about that. Masks block contagious droplets that an infected person breathes out. They also offer a measure of protection for a wearer who's not infected.

So yes, in theory, two is better than one and three is even better, says biosecurity expert Raina MacIntyre, who researches mask effectiveness at the University of New South Wales in Sydney.

But there are pitfalls to piling on masks. You may be more tempted to fiddle with the additional mask, and that's a bad idea if you're in a place where other people have been hanging out and possibly spreading contagious droplets. You might touch a contaminated surface, then bring the viral particles to your mask.

And while a second (or third) mask will create a more effective barrier for outgoing and incoming particles, it will also make it harder to breathe in the air you need.

Adding an additional mask isn't the only way to add a layer of protection. Dr. Abraar Karan, a physician at Brigham and Women's Hospital, recommends a multilayered single mask that fits comfortably snug over your nose and mouth.

Karan and other mask experts look for two or three layers in a mask. Some masks, for example, come with an interior pocket where you can insert a filter. So that adds up to three layers in one face covering.

If you're still interested in doubling up, you might want to consider an innovative approach we wrote about a few months ago.

As correspondent Maria Godoy reported: Researchers at Northeastern University added an outer layer made from nylon stockings to a homemade face covering. They found that the nylon layer can boost a mask's ability to filter out small particles in the air by creating a tighter seal between the mask and the wearer's face.

"Using nylon stockings to improve the fit of a mask makes sense," says Linsey Marr, a civil engineering professor at Virginia Tech who researches airborne transmission of infectious diseases. "The stocking will help reduce or eliminate gaps that would otherwise allow particles to short-circuit the mask."

Does mouthwash offer any benefit in reducing possible transmission of COVID-19?

Imagine gargling the coronavirus away with minty fresh mouthwash! That's what some media headlines suggested in the past few weeks.

The origin of this idea is a study published in September in the Journal of Medical Virology. Researchers at Pennsylvania State University grew the coronavirus in human liver cells, then flushed the cells with mouthwash for durations of 30 seconds and 1 and 2 minutes. Their finding: About 90 percent of the viruses treated with mouthwash lost their ability to infect cells.

But that doesn't mean gargling is the next best thing to a vaccine.

Here's what the optimistic media reports didn't point out.

First, the researchers did not test mouthwash on the coronavirus that causes COVID-19. Instead they tested the strain of coronavirus that causes the common cold.

What's more, they did not test the impact of mouthwash on the coronavirus in actual humans, which makes the study limited, according to Dr. Todd Ellerin, director of infectious diseases at South Shore Health in Weymouth, Mass.

It's not a cure, agrees Dr. Craig Meyers, the study's lead author, and it needs to be tested further on humans.

In the study, mouthwash did not kill the virus, Meyers says; rather, it temporarily stopped it from infecting more cells. The effects are local – so if they were to be replicated in human studies, he believes the mouthwash would only disable the virus that is present in your mouth at the moment of gargling.

In other words, if you're not infected, gargling doesn't protect you from getting infected, says Meyers. While in quarantine, however, an infected person can gargle as a precaution to protect the people around them.

"We're not asking people to do anything like inject this or do anything silly with mouthwash," says Meyers. "We see this as a layer of protection on top of wearing masks and social distancing."

But even a really good long gargle is unlikely to get every bit of virus on each mucus membrane, says Dr. William Schaffner, an infectious disease professor at Vanderbilt University.

"Just wear a mask," Schaffner sighs. "There is no magic solution; pun intended."

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