@BestinthePNW_ @kprather88 @drlucymcbride Nothing is 100%, but you don't need 100% to have a benefit.
Masks are needed if there is close contact and prevalence stays high. No realistic ventilation will stop close range transmission.
@BestInPNW_@kprather88@drlucymcbride没有什么是100%，但你不需要100%就能获得好处。
如果有密切接触且患病率较高，则需要戴口罩。没有实际的通风将阻止近距离传输。