wearing a mask is no big deal in asia
they've been doing it long before the
coronavirus pandemic
western countries have been more
reluctant to adopt face masks as a
useful tool to fight the virus
we don't generally recommend the wearing
of masks in public
by otherwise well individuals because
it has not been up to now associated
with any particular benefit
but eventually opinion changed fancy
home zone masks popped up everywhere
and experts changed their tune people
congregating often without masks
of being in crowds and jumping over
and avoiding and not paying attention to
the guidelines that we very carefully
put out
we're going to continue to be in a lot
of trouble and there's going to be a lot
of hurt
if that does not stop as more variants
of the virus emerged
medical masks were back on the agenda
even becoming mandatory in some places
but can masks really beat the virus
that's the question welcome to our code
with 19 special i'm monica jones in
berlin good to have you with us and
just in case you're wondering why isn't
she wearing a mask
well the studio is pretty much the only
place i can take it off
for now because things keep changing
just like the virus itself
and that also goes for the acceptance of
wearing masks
and the evidence that they really help
curb the spread of the virus
in fact a study from germany has found
that face masks could reduce the number
of new covid19 infections
20 days after their mandatory
introductions
anywhere from 15 to 75 percent
researchers also found that the
reduction in new cases was the most for
those above
60 years of age this is the first study
to identify
causal effects in a population rather
than in a clinical setting
highlighting the correlation between
wearing face masks
and a drop in new infections
klaus velde professor of economics at
the johannes gutenberg university mainz
is the co-author of this study and he
joins me now good to have you with us
what i noticed is that your study
doesn't mention specific
face masks why not
well that's true we don't mention
specific face masks because the
regulation at that time
just required to wear any mask so the
these were probably normal uh self-made
homemade masks
okay so we don't really know about the
efficacy uh
when we take into consideration the
medical masks which are now mandatory in
many places or ffp masks do you have a
hunch
would they be even more effective
well yes of course i mean there are
other studies that study in uh
detail which type of mask is more
effective and we
know of course that uh gloth masks are
not the best one so ffp2 mask as an
example
they have a much better filtering system
okay but apart from the the model or the
material of a face mask
what other factors play a role in in
making wearing a mask effective i
believe your study also points to
different regions different climate
yeah well regions and climate i'm not so
sure but but what definitely matters is
how good a mask fits now if
as a man you wear a beard then of course
there's a lot of
air flow at the edge of the mask and
this can be a problem
and in any case with any mask it depends
on the environment if you are
in a contaminated
if you inhale contaminated ambient air
then you can get
infected anyway i mean uh droplets and
very small droplets they enter anyway
right uh i just had to smile because you
mentioned
beards and i know a few colleagues here
including our science correspondent
uh who will find it difficult to part
with the beard
uh but but back to the efficacy of a
face mask the average
in your study says it's at around 45 47
that's a good start but it means that we
also need different
measures to win this fight which rules
are the most important are all the rules
that we need in place
from your point of view
well it's definitely true masks are not
the only measure we should employ there
should be other rules but
if i uh should say something about rules
i mean rules are one thing
but compliance to rules it's a much
different thing
um when we look for example at the
sudden increase of infections before
christmas
then we this cannot be related to rules
because the rules didn't change at that
time
but we know from mobility data that
around christmas which can be
understood but nevertheless around
christmas mobility increased a lot so
the question is how much compliance is
there
to uh rules in the private uh
environment
and then another issue is for example
the masks
at workplace i recently went to a small
enterprise for
mechanical repairs and everybody was
without mask i mean
i i was shocked i mean so masks at the
workplace
they would all that would be a good
measure as well
exactly and you just mentioned uh
statistics with uh looking at mobility
before christmas i mean we've
we've been flooded with uh statistics on
daily uh infection numbers now for
almost a year now
and more recently sadly we also get the
daily death numbers
but how helpful are those statistics
when it comes to assessing the situation
right now
yeah this is a very uh important uh
question
the daily reported infection numbers
we hear every day they have serious
statistical problems there's a
systematic bias
where does this bias come from well we
test for different
reasons one example is we test when
people go to a doctor and have symptoms
and then we test individuals who had
contact with the person who is infected
or we test individuals that return from
holidays
the statistical problem resulting from
this is when the
relative importance of how many tests
you undertake
because of symptoms or because of
travelers or because of other reasons
when this relative share changes then
the reported number of infections are
not
comparable over time there are of course
other
statistics which are less biased when we
think about
the number of individuals in intensive
care units
i mean this is definitely very unbiased
this is a very good measure
and then as you said the number of
deaths you don't want to hear this but
this is also an unbiased measure but
unfortunately these measures are
delayed i mean this is not instantaneous
measure of how
severe a pandemic is so what we should
do is
we should not just test individuals i
mean testing is
extremely important test as much as
possible but we should also
report why individuals were tested
and if we knew for example all the
positive tests of individuals
that were tested because they had
symptoms
then we should then we would count
covid19 cases so
cases of the disease and this would be
an
unbiased measure of the severity of the
pandemic
okay so there is definitely some
homework to be done certainly when it
comes
to effective testing just very briefly
at what point do you think can we bend
our masks ah
uh well when the pandemic is over simple
answer
okay if if if i had to give a rule
um wait for the number of patients in
intensive care units to fall to a level
that we had in spring 2020
um then we can be more relaxed so we
need to use
unbiased measures and uh on this we can
base
long-term rules and long-term planning
all right
that sounds like a good plan class veda
professor of economics at the hannes
gutenberg university minds and co-author
of the study on face masks thank you so
much
you're welcome
so testing and wearing face masks to
reduce the number of infections
that's half the battle one but some
cases are less easy to trace than others
which brings us to one of your questions
and over to our science correspondent
derek williams
what do estimates now say about the
percentage of infections caused by
asymptomatic cases
to answer this we have to first look at
differences
and similarities in asymptomatic
and pre-symptomatic carriers of covid19
now if someone is infected with the
virus
it might take time to develop symptoms
but
most people eventually do um they're
just
pre-symptomatic for a while one of the
things that's made this disease
so hard to combat is that unlike for
example
people who got sars we think covet 19
patients grow
most contagious late in their incubation
periods so so
while the virus is reproducing rapidly
but before
they begin to show symptoms for some
reason
truly asymptomatic people never develop
symptoms but apparently
go through a similar stage of shedding
the virus
what asymptomatic and pre-symptomatic
people have in common
are those few days where both are
carrying the virus
and shedding it yet neither is showing
any sign of disease
so maybe we should instead ask how many
people are getting covet 19 from people
who aren't showing any symptoms a recent
study
published by cdc specialists tried to
answer
that question the researchers had to
make a couple of educated guesses but
but based on data from other studies
they assumed that close to a third of
all people who catch the virus
remain truly asymptomatic and that
they're around 75 percent as infectious
as those with full-blown disease um if
those baseline assumptions are correct
asymptomatic people would be responsible
for
around a quarter of all covet 19
infections pre-symptomatic transmitters
are thought to pass it along at even
higher rates than that
so so the model therefore predicts over
half of all cases of cobit 19 are
transmitted by people
who have no symptoms at the time they
transmit it
no wonder tracing infection chains has
proven so difficult um
it's more support for the advice that
that wearing masks
in public is a good idea even if no one
around you
is coughing
which brings us back to the topic of
this program that was derek williams of
course and he'll be back to answer more
of your questions again
tomorrow that's all for this edition of
kobe 19 special
but as we're all starved of arts and
culture in these trying times
we want to leave you with some images
from eternal rome
from the coliseum to the vatican museum
which you can visit
again with a face mask of course enjoy
the views
thanks for watching and see you soon
[Music]
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