Face Masks and COVID-19: What You Should Know

By Robyn Abree

By and large, health experts agree: Wearing a mask is a simple, effective way to slow the spread of the novel coronavirus. This may seem like a radical shift from messaging in the earlier days of the pandemic, but there’s a reason for that, says George Rutherford, MD, Professor of Epidemiology & Biostatistics at the University of California – San Francisco.

“Science evolves,” says Dr. Rutherford. “The substantial role that asymptomatic transmission plays in transmitting the virus wasn’t understood until later.”

He also adds experts may have been hesitant to promote mask wearing without much evidence for fear people would hoard medical grade masks that were in short supply.

While it’s unfortunate the messaging has changed, this new understanding can give us a great deal of freedom, says Dr. Rutherford.

“We can shelter in place forever or we can wear masks,” says Dr. Rutherford. “That’s the choice.”

Science Behind Protection

Respiratory droplets from speaking, sneezing and coughing are thought to be the main mode of virus transmission. Masks help curb the spread by trapping infected droplets and preventing them from getting very far.   

Researchers and public health experts stress that the primary reason for wearing masks is to prevent asymptomatic spread of the virus. That is, you wear a mask to protect others if you unknowingly have the virus.

This is still true, but growing evidence suggests that masks provide some protection for the wearer as well, says Richard Wenzel, Professor in the Department of Internal Medicine and Division of Infectious Diseases at Virginia Commonwealth University.  

Dr. Wenzel cites a meta-analysis of 172 studies which looked at various interventions to prevent transmission of SARS, MERS and COVID-19. The study, which was published in The Lancet on June 1, found that wearing a mask significantly reduced a healthy person’s risk of contracting the virus if exposed.

Though the quality of the data was low-to-moderate, Wenzel says this early in the game, this shows “remarkable evidence for the wearer,” and will likely only get stronger as more studies are conducted.

Dr. Rutherford adds that eyewear can give you even more protection. Glasses of any kind will do – they don’t have to be goggles, he says.

Dr. Rutherford also says masks may reduce the amount of virus the wearer is exposed to, possibly resulting in less severe disease if they are infected. Meaning, if someone exhales respiratory droplets close to you, your mask may help block some of the virus. But Dr. Rutherford points out this theory, though shared by other infectious disease experts, has yet to be tested.

But masks by themselves are not foolproof, says Dr. Wenzel. To be effective, masks must be worn by everyone, he says. Even then, there’s still a chance of infection, says Dr. Rutherford. Your best bet to staying protected: Combine mask wearing with social distancing (especially indoors), practicing good hand hygiene and steering clear of anyone not wearing a mask.  

When to Wear a Mask

Get in the habit of wearing a mask any time you leave home, says Dr. Rutherford. The one exception – your car, he says.

This rule applies especially to indoor spaces, and even in outdoor spaces where social distancing is hard to practice, says Dr. Wenzel.

He notes that the 6ft rule came from studies conducted in the 1930s, and new evidence shows that this isn’t enough.

“A single sneeze can travel 20ft,” he says. “Six feet of space won’t protect you if you and those around you aren’t wearing masks.”

There’s also some evidence that suggests smaller virus particles, called aerosols, may linger in the air hours after an infected person has been in the area, says Dr. Wenzel. So, wearing a mask indoors when others aren’t around, particularly in confined spaces like elevators, may protect you from inhaling some of these leftover particles, he says.

Even if you are wearing mask, limit time shared public indoor spaces, if you can help it, says Dr. Wenzel. He notes a recent paper published by the CDC found that infection risk is nearly 20 times higher indoors.

As for doctor’s appointments and other necessary errands, there’s evidence that universal mask-wearing can reduce infection risk, says Dr. Rutherford.

He points to a recent report by the CDC, which looked at a case in which two Missouri hairstylists tested positive for the coronavirus and potentially exposed 140 people. According to the report, both were symptomatic and wearing face coverings, but no new cases or symptoms were tied to the salon. (Note: only 67 clients agreed to get tested for the virus, and social distancing was practiced at the salon, limiting customers to 25% of its capacity).

Study authors noted a few limitations, including that most stylists cut hair while clients are facing away from them, which may also have limited transmission. These findings don’t mean masks are perfect shields, Dr. Rutherford says, but they suggest masks are certainly helpful.

Types of Masks

The amount of protection provided (for both the wearer and for the people around the wearer) depends on the type of mask.  

N95 masks are still in short supply and should be reserved for health care workers and doctors. KN95 masks, which are regulated by the Chinese government, are supposed mimic N95 masks, but testing reveals many in the U.S are fakes or low-quality. Both types of masks are hard to breathe in.

Surgical masks are designed to protect others, but testing suggests that even surgical masks can provide some protection for the wearer. It’s important to buy ones made out polypropylene, which holds a static charge that better traps incoming and outcoming droplets.

Protection from cloth masks depends on the material they’re made out of and how well they fit. But with the right combination of materials, cloth masks can be effective and breathable.

In fact, researchers at Florida Atlantic University found that, when compared to bandanas and cone-style masks found at most pharmacies, double-layered cotton masks were the most effective at reducing forward spread of droplets.

When making or selecting a cloth mask, choose one with multiple layers (at least two) and avoid synthetic fabrics like polyester. Masks made with tightly woven fabrics, like 100% cotton with at least 70 threads per inch. If you’re not sure about the quality of your mask, hold it up to the light. If you can easily see through it, it’s probably not going to give you much protection. 

Shape matters, too. Masks that cup tightly to your face and made with pleats and folds are preferable to those with a flat design. They allow more air flow through the fabric rather than the side of the masks.

Adding a filter to a multi-layered cloth mask can also boost protection. Choose a filter made of two layers of polypropylene. While it’s important to wash your cloth mask after every use, washing filters can reduce their electrostatic charge. Recharge your filters by ironing them or rubbing with a plastic glove until you’ve got static cling.

Bottomline

Wearing a mask is critical for protecting yourself and others but shouldn’t offer a false sense of security. Continue to social distance at least 6 feet, preferably more, from others, wash your hands frequently and limit time in shared indoor spaces.