With only 5,221 confirmed cases and 99 deaths due to Covid-19 up to 08 April 2020, the Czech Republic is one of the countries that has managed best the Coronavirus crisis. It already considers it "under control". This good management is due, among other things, to a measure taken as soon as the virus arrived on their territory: The wearing of a textile mask is compulsory for everyone.
Although protection against particles is not "100%", 80% protection is better than no protection at all. Moreover, if everyone protects themselves, the level of protection is automatically doubled because we are protecting each other. So, even if it is not yet mandatory for us, a piece of advice, go out with a mask on.
Still in doubt? Watch the video.