Large study finds no asymptomatic spread
~10 million subjects in this study
They tested, they traced, and tested again, and found very few asymptomatic positives and no evidence of asymptomatic transmission.
None, nada, zilch.
"The detection rate of asymptomatic positive cases was very low, and there was no evidence of transmission from asymptomatic positive persons to traced close contacts. There were no asymptomatic positive cases in 96.4% of the residential communities.
...
In the present study, virus culture was carried out on samples from asymptomatic positive cases, and found no viable SARS-CoV-2 virus. All close contacts of the asymptomatic positive cases tested negative, indicating that the asymptomatic positive cases detected in this study were unlikely to be infectious."