“In the past year and a half, masking in the United States has gone from being a point of confusion to a partisan flash point. Republicans who have discovered a special enemy in the specter of masking often point back to the morass of conflicting information from the beginning of the pandemic. Yes, Anthony Fauci infamously advised against masking. Yes, the World Health Organization refused to endorse it for months.
“But that was a different time. Wisely navigating a pandemic requires that we marry a healthy skepticism with a willingness to change our minds when presented with high-quality evidence … we should go forward with a more confident thesis about face coverings: Community-wide usage of surgical masks clearly reduces the spread of the coronavirus, especially in the unventilated indoor environments where it seems to spread most efficiently.”
– Derek Thompson, The Atlantic (September 04, 2021)
A review of the literature offers evidence in favor of widespread mask use as source control to reduce community transmission. Nonmedical masks have been effective in reducing transmission of respiratory viruses, and places and time periods where mask usage is required or widespread have shown substantially lower community transmission.
The available evidence suggests that near-universal adoption of nonmedical masks when out in public, in combination with complementary public health measures, could successfully reduce Re (the average number of people infected by one person in a population in practice, including the impact of policies, behavior change, and already infected people) to below 1, thereby reducing community spread if such measures are sustained.
(Jeremy Howard, Austin Huang, et al. “An evidence review of face masks against COVID-19.”
But, do you still want a careful, randomized, real-world experiment to prove the effectiveness of masks in preventing the spread of COVID-19?
Here you go.
A group of scientists from Yale, Stanford, UC Berkeley, and other institutions published the final results of a randomized study of community-wide masking behavior in Bangladesh. The study encompassed roughly 350,000 people in 600 villages. The researchers randomly selected certain villages for an intervention that included giving out free masks, paying villagers to remind people to cover their face, and having village leaders and religious figures such as imams emphasize the importance of masks.
The researchers also paid villagers to count properly worn masks in public places, including markets and mosques. To gather data on coronavirus transmission, the team asked about symptoms and conducted blood tests to determine who came down with COVID-19 over the course of the study.
Their conclusion?
Masks work, period. Surgical masks are particularly effective at preventing coronavirus transmission. And community-wide mask wearing is excellent at protecting older people, who are at much higher risk of severe illness from COVID-19.
The results showed that there were 9.3% fewer symptomatic infections in villages that were targeted in the mask promotion program. The effect was even greater in the villages where the team distributed surgical masks rather than cloth masks. In those areas, infections were 11% lower overall, 23% lower among people between 50 and 60, and 35% lower among people over 60.
Do you think this doesn't sound like a substantial percentage of protection? Think again. The researchers emphasize that this reduction in infections was achieved with just 42% of people wearing masks. The effect of near-universal mask-wearing may be several times larger, they estimate. The increased protection from infection for older individuals, who are more at risk, is also significant.
“It would be a big mistake to infer from our paper that masks can only prevent 10% of infections,” said Jason Abaluck, a co-author of the study and a professor at Yale. He continued: “We think what the results show is that masks are an incredibly powerful tool to reduce symptomatic COVID infections and particularly to reduce symptomatic COVID infections in the people who are most vulnerable to death or very serious illness.”
(Ben Mattison. “In a First, Randomized Study Shows That Masks Reduce COVID-19 Infections. Yale Insights. September 01, 2021.)
Speaking of the “most vulnerable,” In the villages that implemented pro-masking policies, people 50 to 60 years who wore surgical masks were 23% less likely to test positive for COVID compared to their peers who didn't wear masks. For people older than 60, the reduction in risk was greater – 35% . This could be because older villagers are more likely to properly wear masks, or because they are more likely to have symptomatic infections if they come into contact with the coronavirus.
The study also found clear evidence that surgical masks are better at reducing the spread of symptomatic COVID-19 than cloth masks. In focus groups, Bangladeshi participants said they preferred cloth masks because they seemed to be more durable. But the researchers found that, on the one hand, surgical masks were more efficient, even after being washed 10 times with soap and water. “On the other hand, we found only mixed evidence about cloth masks,” said Abaluck.
(Jason Abaluck , Professor of Economics; Ahmed Mushfiq Mobarak , Professor of Economics; et al. “Normalizing Community Mask-wearing: A Cluster Randomized Trial in Bangladesh.” NBER Working Paper Series. National Bureau of Economic Research. April 2021.)
In all, the researchers distributed more than 1 million masks. Free distribution of masks was important. But of all the interventions, mask promotion – that is, paying individuals to remind people on the street to cover their face – seemed to have the biggest effect.
“Reminders from people in the village almost acted as booster shots for masking,” Abaluck said.
Subtler efforts to change behavior failed to do much in the Bangladeshi study. Texting reminders made little difference. Talking about altruism and protecting the community made little difference. Offering cash rewards made little difference. Asking people to post pro-mask signs or to verbally commit to wearing masks in the future made little difference. The behavioral nudges failed to nudge behavior.
(Derek Thompson. “The Masks Were Working All Along.” The Atlantic. September 04, 2021)
What percentage of people need to mask to prevent spikes and deadly spreads of COVID-19?
“What you want is 100 percent of people to wear masks, but you’ll settle for 80 percent,” said epidemiologist George Rutherford, MD. In one simulation, researchers predicted that 80 percent of the population wearing masks would do more to reduce COVID-19 spread than a strict lockdown.
People are sick and tired of lockdowns, so let's review.
Masks work to reduce the spread.
Do your research on the greatest effectiveness of types of masks. N95 masks are considered the gold standard. The blue 3-ply surgical masks generally give more protection than cloth masks. For the most effective filtration in cloth masks, a mask with two woven layers of outside material and some sort of filtering material in the middle – whether that's a coffee filter, surgical mask, or vacuum bag – may be preferred.
Do not wear masks with gaps around the sides of the face or nose.
And, One Caveat From Bangladesh …
The core interventions – which included the free masks and frequent reminders – more than tripled mask use, from 13% in the comparison villages to 42% in the treatment villages. And, people kept wearing masks after the volunteer promoters of masks left the villages.
However …
Medpage Today reports that just 3 months after investigators left Bangladesh, mask usage plummeted, with the bulk of the effect (approximately two-thirds of increase in mask use) being lost. People in these Bangladesh villages were unable to sustain masking after the study ended at the rates seen when the study was ongoing. That shows another limit of the practice. We need to understand what types of interventions lead to long-term adherence to mask-wearing.
Vinay Prasad, MD reports …
“In this study, economists succeeded where public health and medicine failed. One of the big takeaways of the study is that a cluster randomized trial led by healthcare economists succeeded in providing important answers. Economists did what the CDC, public health institutions, and venerable medical organizations failed to do: run a cluster RCT of a non-pharmacologic intervention.”
(Viney Prasad. “Are We Wearing the Wrong Masks?” Medpage Today. September 08, 2021.)
For now, the researchers have turned the best practices from their experiment into a model called NORM, short for:
No-cost free masks distributed door to door.
Offering information about masks.
Reinforcement of mask-wearing behavior in person and in public.
Modeling and endorsement by local leaders.
The international development group BRAC and other partners are now scaling up the NORM model to more than 100 million people across Bangladesh, India, Mexico, Nepal, Pakistan and Uruguay.
(Adela Wu. “A Study In Bangladesh Tripled The Rate Of Mask-Wearing. Can It Help In The U.S.?” National Public Radio. August 13, 2021.)
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