
Face Masks Considerably Reduce Covid-19 Cases in Germany [pdf] - cygx
http://ftp.iza.org/dp13319.pdf
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seesawtron
It is indeed very surprising to see the sharp drop in Covid-19 cases in
Germany.

If I understand correctly, this is also not a randomized trial. I am not sure
how they constructed the "control" group here to which they are comparing. It
is a synthetic group where they extrapolate cases from n-7 days where n is the
day of introduction of mandatory use of masks?

It is hard to not be tempted to think about several confounding variables that
could have played a role in the drop that is seen, like people being more
vigilant, following distance guidelines, working from home more often, the
list goes on. Nevertheless, it was an interesting read.

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cygx
_Abstract:_

We use the synthetic control method to analyze the effect of face masks on the
spread of Covid-19 in Germany. Our identification approach exploits regional
variation in the point in time when face masks became compulsory. Depending on
the region we analyse, we find that face masks reduced the cumulative number
of registered Covid-19 cases between 2.3% and 13% over a period of 10 days
after they became compulsory. Assessing the credibility of the various
estimates, we conclude that face masks reduce the daily growth rate of
reported infections by around 40%

