12/14/2020    Multiple Respondents

Medical Face Masks: An Overview for General Usage and Simple Guidelines (Jon Purdy, DPM)

Dr. Purdy may have read about this study on
social media as the authors generated a lot of
publicity spreading this around long before they
could find an actual journal to publish it.
Sadly, the article's abstract says this:

Limitation: Inconclusive results, missing data,
variable adherence, patient-reported findings on
home tests, no blinding, and no assessment of
whether masks could decrease disease transmission
from mask wearers to others.

and the executive editor of the British Medical
Journal commented thusly regarding the
conclusion:

If you read the published paper you find almost
the exact opposite.345 The trial is inconclusive
rather than negative, and it points to a likely
benefit of mask wearing to the wearer—it did not
examine the wider potential benefit of reduced
spread of infection to others—and this even in a
population where mask wearing isn’t mandatory and
prevalence of infection is low. This finding is
in keeping with summaries of evidence from
Cochrane.

Richard Rettig, DPM, Philadelphia, PA

From the study Dr. Purdy cites:
“Inconclusive results, missing data, variable
adherence, patient-reported findings on home
tests, no blinding, and no assessment of whether
masks could decrease disease transmission from
mask wearers to others.”

It makes sense to limit salt intake despite
little scientific evidence doing so lowers blood
pressure, but we advise patients to do so because
it makes scientific (nephrological) sense. I
remember reading a study that showed infection
rates weren’t any lower if the surgeon didn’t
wear a mask. Do you want YOUR surgeon to not
wear a mask?

Sometimes, common sense takes over when science
has yet to catch up.

Keep in mind this “study” was funded by The
Sailing Foundation, a Danish merchant who may
have an agenda.

Howard R. Fox, DPM, Staten Island, NY

Why are we listening to such nonsense as this
response by Dr. Purdy's reference to a study
showing that masks don’t prevent viral
transmission. Below are the pertinent facts
stated in the study: The results are
inconclusive. There is missing data.
There is variable adherence. There is no
blinding. There is no assurance of whether masks
could decrease transmission from mask wearers to
others.

This study is flawed from its outset and to
publicize it as "fact" is fraudulent and
dangerous

Brian Kiel, DPM, Memphis, TN

Dr. Jon Purdy cites a Danish study (May 2020)
"showing mask usage does not lower infection
rates."

The study states, in limitations, "No assessment
of whether masks could decrease disease
transmission from mask wearers to others."
You wear a mask to reduce the chance of infecting
OTHERS.

If you want to increase protection for the
wearer, use a better mask. The point is to at
least slow the spread of COVID-19 until those who
choose to can be vaccinated.

Is it really that big a deal to ask people to be
considerate of other people?

Joseph Weisenfeld, DPM, Staten Island, NY

Interesting study from Dr Purdy. One thing that I
would like to point out is the study only said
that it does not prevent a person from becoming
infected. What it did NOT say is whether the mask
protected other people from becoming infected if
that person is infected.

Limitation: Inconclusive results, missing data,
variable adherence, patient-reported findings on
home tests, no blinding, and no assessment of
whether masks could decrease disease transmission
from mask wearers to others.

So, do we want to help others from getting
infected, or do you care? Dr. Fauci has said many
times that the purpose of masks is to protect
other people.

Richard Rees, DPM, Bellaire, TX

Other messages in this thread:

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12/11/2020    Warren S Joseph, DPM

Medical Face Masks: An Overview for General Usage and Simple Guidelines (Jon Purdy, DPM)

In response to Dr. Purdy’s comment about the
Danish Mask wearing study, it should be noted
that this was only one study, versus many showing
effectiveness of mask wearing, and significant
limitation to that study have been elucidated by
multiple sources. One of the most definitive
resources is the Infectious Diseases Society of
America who maintains an entire webpage dedicated
to ALL studies about mask effectiveness that is
continuously updated. The link to that page is
here:

Masks & Face Coverings for the Public
(idsociety.org)

These are their conclusions about limitations of
the Danish study:

Limitations:
• 20% of the study population did not complete
the study.
• Only 46% of the individuals in the intervention
group wore masks as recommended.
• The sample size was insufficient to determine
the statistical significance of a 20% reduction
in infections.
• This study was performed in a setting with
relatively low transmission. During the first
week of May, the daily incidence of new confirmed
COVID-19 cases in Denmark was one-quarter of
daily incidence in the United States.
• The effect of a mask recommendation also
depends on other factors including the prevalence
of the virus, physical distancing adherence and
the frequency and characteristics of gatherings.
• Of COVID-19 diagnoses in this study, 84% (80 of
95) were made using antibody tests, whose
accuracy varies.

Overall, in this large population-based
randomized controlled trial, recommending persons
to wear masks in addition to social distancing
was not associated with reduction in SARS-CoV-2
acquisition for mask wearers. The study is
limited by a significant amount of mask non-
adherence in participants recommended to wear
them and by the fact that community caseload was
low during the study. The results also cannot be
extrapolated to determine the effectiveness of
masks at reducing transmission of SARS-CoV-2, as
the study was designed to assess protection of
wearers, not transmission.

Warren S Joseph, DPM, Hatboro, PA