[Rushtalk] Little Evidence Supports Use of Cloth Masks to Limit Spread of Coronavirus: Analysis

Carl Spitzer {C Juno} cwsiv at juno.com
Tue Nov 16 07:40:07 MST 2021

Little Evidence Supports Use of Cloth Masks to Limit Spread of
Coronavirus: Analysis
By Zachary Stieber
November 15, 2021 Updated: November 15, 2021 
Cloth masks are of little use against COVID-19, according to a recently
published analysis.

Federal health authorities and a slew of jurisdictions require or
recommend wearing masks as a way to limit spread of the virus that
causes COVID-19.

But a trio of researchers pored over the studies often cited by the
officials and found they were poorly designed and offered scant evidence
supporting mask usage.

Many of the studies are observational, opening them up to confounding
variables, the researchers said in their analysis (pdf), which was
published on Nov. 8 by the Cato Institute.

Of 16 randomized controlled trials comparing mask effectiveness to
controls with no masks, 14 failed to find a statistically significant
benefit, the researchers said. And of 16 quantitative meta-analyses,
half showed weak evidence of mask effectiveness while the others “were
equivocal or critical as to whether evidence supports a public
recommendation of masks,” they added.

“The biggest takeaway is that more than 100 years of attempts to prove
that masks are beneficial has produced a large volume of mostly
low-quality evidence that has generally failed to demonstrate their
value in most settings,” Dr. Jonathan Darrow, an assistant professor of
medicine at Harvard Medical School, told The Epoch Times in an email.

“Officials mulling mask recommendations should turn their attention to
interventions with larger and more certain benefits, such as vaccines.
Based on the evidence currently available, masks are mostly a
distraction from the important work of promoting the public health,” he

One widely-cited study (pdf) by mask proponents, of rural villages in
Bangladesh, found that surgical masks appeared to be marginally
effective in reducing symptomatic COVID-19 but that cloth masks did not,
Darrow and his colleagues noted. The other real-world randomized
controlled trial examining mask effectiveness, conducted in Denmark, did
not find a statistically significant difference in infections between
the masked and unmasked groups.

“The remainder of the available clinical evidence is primarily limited
to non-randomized observational data, which are subject to confounding,”
the researchers said, including accounting for other differences in
behavior among those who don’t wear masks.

They did say that there is evidence masks reduce droplet dispersion,
though cloth masks are unlikely to capture the particles even if worn

Due to the COVID-19 pandemic, policymakers cannot wait for
higher-quality evidence to support masking, but from an ethical
standpoint, they should “refrain from portraying the evidence as
stronger than it actually is,” the researchers concluded.

COVID-19 is the disease caused by the CCP (Chinese Communist Party)
virus. The CCP virus is also known as the coronavirus, or SARS-CoV-2.

Some outside experts’ views align with the researchers, including Dr.
Martin Kulldorff, senior scientific director of the Brownstone

“The truth is that there has been only two randomized trials of masks
for COVID. One was in Denmark, which showed that they might be slightly
beneficial, they might be slightly harmful, we don’t really know—the
confidence interval kind of crossed zero,” he said. “And then there was
another study from Bangladesh where they randomized villagers to masks
or no masks. And the efficacy of the masks was for reduction of COVID
was something between zero and 18 percent. So either no effect or very
minuscule effect.”

Some experts, though, say the existing evidence does support masking
recommendations, and several reacted strongly to the new analysis.

The analysis drew some pushback, including from Kimberly Prather,
director of the National Science Foundation Center for Aerosol Impacts
on Chemistry of the Environment.

Prather noted on Twitter that researchers said masks reduce the amount
of virus in the air and believed that ran counter to their conclusions.

Darrow responded by saying the amount of virus in the air was a
surrogate, not a clinical endpoint.

“The amount of pathogen in air (to be inhaled) directly determines the
dose. This is directly linked to risk,” Prather added. “Or can you
explain how less virus in the air could be higher risk? It’s equivalent
to saying that less pathogen in drinking water is higher risk so don’t
filter water.”

“If the theory diverges from what you see in real life, which one do you
believe?” Darrow said.

Zachary Stieber
Zachary Stieber
Zachary Stieber covers U.S. news, including politics and court cases. He
started at The Epoch Times as a New York City metro reporter.


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