At the start of the pandemic, which started in China, there was a rush to buy face masks in Hong Kong, where people remember the impact of SARS.
Dr Yuen told a press conference on Sunday: "In our hamster
experiment, it shows very clearly that if infected hamsters or humans - especially asymptomatic
or symptomatic ones - put on masks, they actually protect other people.
rate dropped by about 35% when masks were placed on the healthy hamsters' cage.
According to a study by a team in Hong Kong, the rate at which the virus
was transmitted through airborne
particles or respiratory droplets was lowered by as much as 75% when masks were used.
Walking around without a face mask in Hong Kong, Japan
or North Korea is seen as irresponsible, and several US states are also now advising people to wear them when out.