A huge study out of China demonstrating, for the umpteenth time, that there is no such thing as an asymptomatic spread of COVID. This has been known for months but the value of the study is it’s enormous volume.
Lack of asymptomatic transmission is one of the reasons why masks are completely useless.
The study also demonstrates that “cases” are a useless metric.
Before anybody starts on the “but it’s China” tangent, we have known this for months because every study from everywhere has come up with the same conclusions.