Without defence, diseases become epidemics. Whether transmitted through the skin, fluids or air, hygiene is the first line of defence against infection.
Vaccination and the general rules of hygiene are therefore effective and necessary. In the case of corona viruses, however, more is needed: additional air hygiene.
With Covid-19, the greatest danger is the long residence time of the viruses in the indoor air. Outdoors, the aerosols spread very quickly but, indoors they can hover and concentrate in the same place for a long time.
Thus, it is important to bring in fresh air and ventilate while effectively destroying viruses with UV-C light. It destroys the DNA of viruses and bacteria. Modern UVC devices are light-proof and harmless, the technology has been used in hospitals, the food industry or waterworks for a very long time.