Tom Jefferson, an epidemiologist and honorary research fellow at the Centre for Evidence-Based Medicine at the University of Oxford, said the findings were “very, very important.” He told The BMJ,

“The sample is small, and more data will become available. Also, it’s not clear exactly how these cases were identified. But let’s just say they are generalisable. And even if they are 10% out, then this suggests the virus is everywhere. If—and I stress, if—the results are representative, then we have to ask,

‘What the hell are we locking down for?’

Covid-19: four fifths of cases are asymptomatic, China figures indicate. Michael Day, British Medical Journal