Cloth masks offer some COVID-19 protection, but surgical masks are better, experts say based on latest research
‘We had evidence that we get some protection from cloth masks,’ one expert says. ‘And we now have newer evidence that we get better protection from surgical masks.’
Cloth masks sprang into fashion when surgical masks and N95s were harder to find in the pandemic’s early days. The federal Centers for Disease Control and Prevention still promotes cloth face coverings in its guidance about masks.
And masks remain a critical tool because people primarily become infected with COVID-19 by inhaling small aerosol particles that linger in the air or large respiratory droplets produced in coughs and sneezes.
But the science is changing. Delta, currently the primary variant in the United States, is far more contagious than the original coronavirus, so the density of virus in the air is greater.
As a result, some experts have adjusted their advice on masks.
“Given the Delta variant that’s out there, you probably need to upgrade your mask,” Dr. Ashish Jha, a COVID expert and dean of the Brown University School of Public Health, told Fox News earlier this month.
WHAT TYPE OF MASK SHOULD YOU WEAR?
Mask guidance has been mixed since the dawn of the pandemic. First, people were told masking wasn’t necessary. Soon after, this recommendation changed, but the public was advised against buying surgical masks because of shortages. Americans instead were told to buy cloth masks or make their own.
Shortages don’t appear to be as big a problem now, but the CDC still advises against choosing N95 respirators.
As recently as late August, the nation’s top infectious-disease doctor, Dr. Anthony Fauci, declined to recommend higher-quality masks.
“Instead of worrying about what kind of mask, just wear a mask,” Fauci said on MSNBC.
So what gives? Dr. Peter Chin-Hong, an expert on infectious diseases at the University of California-San Francisco, said Fauci was taking a harm-reduction approach.
“It probably is more important to wear something that you feel comfortable with, and you can wear for long periods of time if you’re going into a particular environment … rather than saying you need to wear the gold standard thing at all times,” Chin-Hong said.
Still, he said, “A baseline should be a surgical mask.”
While Chin-Hong thinks government and public health officials should emphasize wearing surgical masks, he said cloth masks can offer enough protection in certain circumstances. He said a fully vaccinated person would likely get adequate protection from a cloth face covering for brief periods indoors when the venue isn’t at capacity.
To help decide, he suggesting asking yourself:
- If you are going indoors, will the building be especially crowded?
- How long will you be inside?
- Will everyone most likely be masked?
- Are you and others around you fully vaccinated?
- Are you immunocompromised?
The riskier the situation, the more likely a higher-quality mask is the better option, Chin-Hong said.
“Masks need to be stepped up to fight Delta, but it does not mean those who cannot afford N95s have no options,” said Raina MacIntyre, head of the biosecurity research program at the University of New South Wales in Sydney, Australia, who has conducted many studies on masks.
MacIntyre said it’s “possible to design a high-performing cloth mask.” An experimental lab study she co-authored found a layered cloth mask can effectively block droplets. The study, published in May in the journal ACS Biomaterials Science & Engineering, recommends using a minimum of three layers — a combination of cotton/linen and polyester/nylon — to resemble the droplet-blocking performance of surgical masks.
Not only is layering important to improve filtration, so is fit. A CDC-recommended technique for improving the fit of a cloth or surgical mask is knotting the straps and tucking the sides. A mask generally is a good fit if you feel warm air coming through the front of the mask as you inhale and exhale.
WHAT DOES THE RESEARCH SHOW?
A large-scale, real-world study published this month found surgical masks are especially effective at reducing symptomatic infections. These types of masks prevented one in three infections among people 60 and older.
Researchers from Yale, Stanford and the nonprofit GreenVoice monitored more than 340,000 adults in rural Bangladesh for at least eight weeks. Roughly half received interventions like free mask distribution and promotion. Villages that did saw mask use jump from 13% to 42% and reported fewer confirmed COVID infections and a lower incidence of symptoms.
Villages where cloth masks were given out reported an 8.5% reduction in symptoms. Villages that received surgical masks reported a 13.6% reduction.
When a third of adults with symptoms commonly associated with COVID agreed to get their blood tested for the virus, the researchers saw an 11% reduction among those who wore surgical masks. By comparison, they observed a 5% reduction in infections among those who wore cloth masks.
This study — conducted before the Delta variant was circulating widely in the country — has not yet undergone peer review, but some experts already have heralded its methodology and results.
“When I saw those results, I threw away my cloth mask,” said Dr. Stephen Luby, a co-author of the study who is a professor of infectious disease at Stanford University. “If Delta is circulating and if you’re going to wear a mask, why don’t you wear one that the data tell you is good?”
“We find very strong evidence that surgical masks are effective,” said Jason Abaluck, an economist at Yale who helped lead the study. “My read of that is that cloth masks are probably somewhat effective. They are probably better than nothing.”
Abaluck suspects his study offers mixed evidence for cloth masks because only about a third of those who reported symptoms consented to blood testing for COVID, so the sample size was too small to observe anything significant.
“The most likely interpretation of this whole constellation of results is that [cloth masks] actually do help,” Abaluck said. “They actually do make you less likely to get COVID. That’s why we saw fewer symptoms.”
Multiple observational studies and trend analyses have found that community masking, which includes the use of cloth masks, reduces the spread of COVID. The researchers in the Bangladesh study said those studies had drawbacks, though, which is why they conducted a randomized clinical trial. But they agreed with those studies’ overall assessment: People who wear masks are less likely to get infected than people who don’t.
“This is the nature of science: Science evolves,” Luby said. “We had evidence that we get some protection from cloth masks. And we now have newer evidence that we get better protection from surgical masks.”
KHN(Kaiser Health News) is a national newsroom that produces in-depth journalism on health issues.