According to one study, the wearing of masks in the mouth has prevented tens of thousands of new infections in Italy and in the city of New York every time. According to the scientists, the air-borne transmission of Sars-CoV-2 is the major route of infection.

In Italy, the measure has helped to prevent more of 78,000 new infections between 6 April and 9 may, in New York city over 66,000 between 17 April and 9 may, were calculated by researchers from the University of Texas and California in the journal Proceedings of the National Academy of Sciences (PNAS).