If it's a good quality mask, that would be misunderstanding the words on the box. Masks provide some protection against the spreading of liquid droplets, as it

If it's a good quality mask, that would be misunderstanding the words on the box. Masks provide some protection against the spreading of liquid droplets, as it says on the box. (Quality of mask varies a lot, though.) In the case of Covid-19, droplets are believed to be the primary way it is suspended in air and breathed in by the next person. Although that type of mask doesn't protect against pure airborne virus transmission without droplets, that is more applicable to other viruses than Covid-19. The key difference: "Airborne virus" means virus without droplets (or such tiny ones that it's not what we mean by droplets); it does not mean the same thing as virus carried by small liquid droplets of the size normally breathed out by humans, and attenuated by cloth masks. Maybe some Covid-19 is transported without droplets, but quantity of exposure matters, and suppressing droplet transmission, as done by good cloth masks, still has a significant effect. There are better, more thorough mask types available, of course.