One of the biggest difficulties that health watchdogs saw during the COVID pandemic was the rising number of asymptomatic patients. These patients were unaware of carrying the virus as they didn't experience any symptoms of the infection. But these people were as efficient as those who showed symptoms, in spreading the virus.
In this case, masks would serve as the first and foremost protection to the healthy individuals. Masks would stop the viruses present in the droplets of breathing, sneezing and cough of the infected individuals, both symptomatic and asymptomatic, from entering the body of a healthy person.