Hello, welcome to my channel Medicine with Dr. Moran. Today's question is to mask or not to mask?
There are still mass mandates in areas in North America as well as around the world. There was
a lot of press coverage in the past week where a federal judge in Florida struck down the U.S.
government's mask mandate for planes and trains. This was announced mid-flight by
pilots and cheered by many passengers. You've probably seen the videos by now.
The CDC however continues to recommend masking on planes. the question is what's the evidence
and our problem in medicine is that there's not been a cluster randomized controlled
trial of masking versus no masking in this situation and of course what mask do you wear?
One cluster randomized masking trial was done in Bangladesh. Now this was done prior
to vaccinations in a non-immune population in Bangladesh from November 2020 to April 2021.
The study participants had not been previously infected or been vaccinated. I made a video on
this and there's a link in the description below. Ultimately they found that cloth masks were not
helpful in the villages that wore those. There was only a 5% reduction which was not statistically
significant. The cloth masks that they wore were three ply and they had a polypropylene coating
with a nose piece so we're not talking about the typical cloth mask that most people wear.
Now there was a significant 11% reduction in the villages that wore surgical masks and this was
just statistically significant with a p-value of 0.043. That means there's a 4.3% probability
that the difference occurred by chance. Many people in the media took the study to show
that masks worked but it was only the surgical masks that had a very small reduction and not the
cloth masks. When the raw data was actually looked at by a number of external reviewers
after it was published the benefit was believed to be even lower than this.
Our only other randomized masking trial was done in Denmark. This did not demonstrate a
statistical benefit in people wearing a surgical mask versus not wearing a mask. There was a
reduction from 2.1% down to 1.8% comparing the unmasked to surgically mass participants
which is about a 15% drop. This did not come close to achieving statistical significance.
The study itself actually was underpowered to detect such a small difference and what I mean
by that is if there had been more people in the study and there continued to be a 15% reduction
with surgical masks then that could have eventually been clinically significant
but that's simply speculation whether the trial would have continued to go in that direction.
In any event these numbers are exceedingly small 11 and 15 and they're not what most people would
think of given the mandates that you hear. I've flown on planes four times during the pandemic
and most people either wear a cloth mask or a surgical mask. The thing about the mandate is
that it only applies for some of the time if you're eating or drinking the mandate simply
miraculously goes away if you're in first class and you served a meal with multiple drinks you may
not have your mask on for a large portion of the flight. It's just like the school mask mandates
for toddlers that suddenly get lifted every day when it's time for the toddlers to take a nap.
So again were there any medical studies run to take a look at the questions of masking on planes
and again the answer is no. It would have been very helpful to know whether cloth masks,
surgical masks, or even higher filtration masks like the N95,
or KN94 were helpful or not. If they were helpful it would be nice to know what the effect size is
in other words how much of a reduction in risk you would get by wearing a mask.
Also knowing whether that varies based on the community prevalence of the virus where the
traveler origin flight takes off from as well as the level of immunity in the population.
The study could also separately look at whether it's different if you're allowed to take your
mask off briefly to have a snack or drink. This would have been very helpful and would give people
a better idea about the risk of traveling and the benefits of the different types of masks.
Remember that the situation is a lot different now than when the Bangladesh and the Danish
studies were actually done. Why? because there's a majority of people in countries have been either
previously infected and a large majority also have been vaccinated so we've got two kinds of immunity
in the population. This was not the case of course with these two studies. Thus it actually would
be harder now to show benefit because a large percentage of the population either has immunity
through natural infection or by vaccination and so the likelihood of getting infected as well
as the likelihood of hospitalization or death has already been markedly reduced. I know there
have been a lot of laboratory studies looking at filtration with different masks and obviously a
cloth mask will filter large particles but it's one thing to do testing at the lab bench and it's
another thing to know the effects in real life. We all want to know what it's like in real life.
One of the problems of course with the pandemic was the initial reluctance to accept the fact
that this actually is an airborne illness with tiny particles less than 5 microns
which can stay in the air for a period of time just like smoke and will easily go through cloth
and surgical masks. In the beginning of the pandemic some felt that this was transmitted
predominantly by droplets which are much larger and might be blocked by a cloth or surgical mask.
I worked through the original Sars pandemic back in 2003 where we were all wearing N95 masks all
the time due to the airborne transmission of this Sars corona virus. For this reason I let many of
my high-risk patients know at the beginning of this pandemic that the best mask is an N95 if
it's available to them. Many patients actually had one or two of these masks at home because
they're often used in renovation or construction projects to prevent dust from getting into your
mouth or nose. There was a recent meta-analysis published looking at the different kinds of masks
against respiratory virus infections. There is a link in the description below if you're
interested. Now in the study they found that evidence supporting the use of surgical masks
against influenza or coronavirus infections meaning Sars, MERS, and Covid-19 was very weak.
An N95 or equivalent mask were found to be the most effective in providing protection against
different types of coronavirus infections due to its filtration properties. Anecdotally we
know that N95 masks are helpful because we're using them caring for Covid-19 patients in the
hospital every day. Typically when hospital staff acquire covid from patients it's often
traced back to when the mask is off such as in the break room that the staff would have.
So ultimately when it comes to masks it's all about the mask that you wear
and the fit of the mask. If you're someone that's elderly or with comorbidities and the
community prevalence is high of the virus and of course you're going into an indoor situation
it's quite reasonable to wear an N95 or KN94 mask. Currently in parts of the world masks are optional
but some choose to make a personal choice to wear one and we have to remember to be respectful to
those that choose to mask. Remember that it's their freedom to do that and I think all of us
want freedoms. Now the mask fit is important and that's the reason why healthcare professionals
get a mask fitting regularly every year or two and these masks have different shapes
and we all have different shaped faces and you want to make sure that you're wearing a
mask that fits to the contour of your face. Typically we test the mask by introducing
a test agent with a smell into the air and see if the mask wearer can actually detect it. If you can
smell it the mask is not going to provide the best protection and you need to try a different mask.
People ask whether mass mandates are working to reduce cases. There have been observational
studies some of which suggest case may be lower and others which come to the opposite conclusion
that mass mandates do not reduce cases. The problem is that the majority of these studies do
not control for confounders in the two groups that they're comparing. They're simply observational
studies not proper randomized studies and the two groups in the studies are often different
because of immunity status, vaccination rate, personal mobility, and other possible confounders.
Now the one thing we do know is there is some harm in mask mandates when it comes to children. We're
starting to see multiple studies now in children who have been masked in terms of their early
personal, emotional, and social developmental milestones. The U.S. and Canada were the only
countries that I know of to mask children from the age of 2 and up. The WHO recommended against
masking children under the age of six and the Scandinavian countries never required masks for
children under the age of 12. In general when you see different countries doing different things it
tells you that the research is not clear on what the best thing is to do. That's always something
to keep in mind. I want to briefly point out that there have been a couple of observational studies
in children of interest with respect to masking one is from Spain and the other from Finland.
There are links below to the studies. Now there are limitations because these are obviously
observational studies. The study in Spain in their pre-print which is not peer-reviewed they looked
at 599,000 children and children between the age of 3 and 5 in the preschool group did not have a
face covering mandate but kids in the 6 to 11 years of age group in the primary school did.
They found that infection as well as transmission was lower in the preschool group as you can see
on this graph. The six-year-old children who were masked had a higher incidence of
infection than the five-year-olds who did not mask and this was statistically significant
as you can see on the graph. Now there was an increase in infection as age increased
but if masks were helpful one might have expected there to be a drop starting at the age of six
where there was a mass mandate and this was not found in the study.
The percentage of infections was 3.54% for the six-year-olds versus 3.1% for the five-year-olds.
Now the study from Finland is also a pre-print and it's not peer-reviewed. In Finland the
recommendation was to use face masks in school for students 12 years 12 years of age and above
as I've mentioned previously. they looked at two cities in Finland Helsinki and Turku.
Helsinki has a population of 660,000 and they mask their students 12 and older whereas Turku
which had a population of 195,000 had an extended recommendation that masking would be for students
10 years and up. Both cities had the same incidence of Covid infections in August and
September of 2021 and they look subsequent to that date at infections in the different ages
of children looking specifically at the 10 to 12 year old group. They compared both cities and they
did not see any significant differences when they looked at the 10 to 12 age group. Again there's
obviously some limitations to this observational study because there could be differences between
these two cities or the schools and of course schools are not the only place where children
have social contacts and can be exposed to the Coronavirus but once again a randomized study
looking at masks in different age groups would have been helpful instead of me quoting these
observational studies which have limitations. We've known for a long time that this virus is not
going away and it's going to continue to circulate and there will be future waves and new variants.
It would be helpful to know the risks and benefits of masking in different age groups
and which types of masks and of course when they might be beneficial to be worn. That way we'd
be basing public health policy on real-world evidence-based medicine. That's what we need.
It builds trust for the public. In summary we have no evidence that cloth masks are actually helpful.
The data that I presented for surgical mass suggests that the benefit has a small effect size
but really with low certainty of evidence. High filtration masks such as the N95 or KN94 are much
better although we don't have randomized control trials in the real world using these masks.
They're also much harder to wear for longer periods of time which I can attest to.
So the bottom line is if you need to wear a mask choose an N95 or KN94 if you want the
best protection. Thanks for joining me today on Medicine with Dr. Moran.
My name is Dr. Keith Moran and remember get healthy and stay healthy.