Those that wore masks had 60% higher rates of asymptomatic infection. That means that mask wearing decreased the severity of Covid-19 if the mask wearer is infected. The masks first line of defense is against droplets shared amongst humans in close proximity. The second line of defense is the buildup of humidity that causes mucus and aids the cilia (really tiny hairs) to be bathed in moisture. This combo of mucus, cilia, and moisture helps to trap viruses and transfer them to the stomach where they are destroyed, rather than letting them embed into the respiratory system.