  The effect of masking the general population on a COVID-19 epidemic is
estimated by computer simulation using two separate state-of-the-art web-based
softwares, one of them calibrated for the SARS-CoV-2 virus. The questions
addressed are these: 1. Can mask use by the general population limit the spread
of SARS-CoV-2 in a country? 2. What types of masks exist, and how elaborate
must a mask be to be effective against COVID-19? 3. Does the mask have to be
applied early in an epidemic? 4. A brief general discussion of masks and some
possible future research questions regarding masks and SARS-CoV-2. Results are
as follows: (1) The results indicate that any type of mask, even simple
home-made ones, may be effective. Masks use seems to have an effect in lowering
new patients even the protective effect of each mask (here dubbed "one-mask
protection") is low. Strict adherence to mask use does not appear to be
critical. However, increasing the one-mask protection to > 50% was found to be
advantageous. Masks seemed able to reduce overflow of capacity, e.g. of
intensive care. As the default parameters of the software included another
intervention, it seems possible to combine mask and other interventions. (2)
Masks do seem to reduce the number of new cases even if introduced at a late
stage in an epidemic. However, early implementation helps reduce the cumulative
and total number of cases. (3) The simulations suggest that it might be
possible to eliminate a COVID-19 outbreak by widespread mask use during a
limited period. The results from these simulations are encouraging, but do not
necessarily represent the real-life situation, so it is suggested that clinical
trials of masks are now carried out while continuously monitoring effects and
side-effects.
