Nothing is bulletproof, all we can do is take actions to reduce probability of transmission and the actions chosen should target the greatest drivers of transmi

Nothing is bulletproof, all we can do is take actions to reduce probability of transmission and the actions chosen should target the greatest drivers of transmission. I am not aware of any studies but on the other hand it would be incredibly easy for cases of asymptomatic spread to actually have been infected by a symptomatic person, in a chaotic environment it's difficult to get good data.