In April, the first recommendation for mask-wearing was to protect others—your family, friends, and the older adult or immunocompromised person at the grocery store. Now, though, the growing body of evidence suggests that wearing a mask to prevent the spread of SARS-CoV-2—the virus that causes COVID-19—is key to protecting yourself too, according to the Centers for Disease Control and Prevention (CDC). As knowledge of masks and their benefits continue to evolve, physicians want patients to know what to look for when choosing one to wear.
“The science is really clear on this—that masks are an important way that we can all slow down and prevent the spread of COVID-19,” said Preeti Malani, MD, chief health officer and professor of medicine in the infectious diseases division at the University of Michigan. Dr. Malani is also associate editor of JAMA.
During a time where cases are surging, it’s essential to practice physical distancing and avoid gatherings, “but basically anytime you’re with anyone not in your immediate household or in any public space when you’ve left your house, we should be wearing a mask,” said Dr. Malani. “It should be part of our uniform, like you would wear shoes.”
“It’s just become something that people have gotten used to. At the same time, there are people who don’t want to wear masks and science is not necessarily guiding that, though,” she said. “The science is clear on this—that masks are really the most important thing we can do right now while we wait for the vaccine to be widely available.”
Because SARS-CoV-2 is transmitted predominantly by respiratory droplets generated when people talk, breathe, sneeze or cough, the CDC recommends community use of masks. With this new guidance from the CDC, Dr. Malani offered advice on choosing the right mask to stop the spread of COVID-19.
The use of multilayer cloth masks can block 50–70% of fine droplets and particles. They can also limit the forward spread of droplets and particles that are not captured, notes the CDC. In fact, upwards of 80% blockage has been achieved with cloth masks in some studies, which is about on par with surgical masks as barriers for source control.
Other materials, such as silk masks, may help repel moist droplets. They may also reduce fabric wetting, which can help maintain breathability and comfort for the wearer.
“There was a situation on our campus where people were blowing out candles through the mask that was given to the students and were saying, ‘Well, see this is a bad mask,’” said Dr. Malani. However, “the droplets of viruses are different. Just because you can blow through the mask doesn’t mean it’s not useful.
“But, in general, you want something that is thick enough,” she added.
Some materials can also enhance filtering effectiveness by generating “triboelectric charge,” which is a form of static electricity, says the CDC. This enhances capture of charged particles. While Dr. Malani wears a surgical mask all day at work, she emphasized the need to “change those out every day.”
Medical masks are “disposable—they’re not meant to use over time,” she said. “What I’ll do is I’ll wear an old one in and then I’ll toss it out and put the new one on as they hand it to me.”
Additionally, “if the mask becomes soiled or wet, you should change it out too,” said Dr. Malani.
When choosing a mask, ensure that it fits properly. That means it is snug around the nose and chin without large gaps around the sides of the face.
“Wear a good quality cloth mask that's comfortable,” said Dr. Malani. “Wear it consistently and make sure it covers your mouth and nose completely.”
However, avoid ill-fitting masks such as spandex neck gaiters.
“If you watch college football, you’ll see about half the coaches’ faces are exposed because those gaiter masks don’t stay in place for most people,” said Dr. Malani, adding that “gaiters are not lined, which was one of the concerns about them.”
“A cloth mask is just a good idea because it stays up,” she said. “Gaiters don’t. You end up messing with them a lot.”
Watch this “AMA COVID-19 Update” episode on what doctors wish patients knew about wearing masks.
It is important to note that surgical masks and N95 masks that are meant for health professionals should not be used. This is because surgical masks and respirators are critical supplies needed for physicians and other health professionals to prevent supply shortages, says the CDC.
While these masks appear to be widely available in drug stores and online, they are not for health professionals. For health professionals, fit testing is essential for picking the right size of N95 masks to ensure it functions properly.
“There may be some circumstances where someone in the community would benefit from the N95 mask, but, in general, those are ones that we also like to save,” said Dr. Malani. “Even in the hospital, we don’t use them for everything. We use them for the known infections because we’re in short supply.”
The CDC offers further guidance on considerations for wearing a mask to help slow the spread of COVID-19.