"Mainland China and South Korea have reduced the number of reported new covid-19 cases down to around 100 a day or less; Hong Kong, Singapore and Taiwan never saw steep rises in the first place (see chart 1). Now they all face the same challenge: how to limit the all-but-inevitable rise in cases that will follow when they relax current controls, a rise which can already be seen in some places. To meet that challenge they are all turning to information technology.
Their efforts, like others elsewhere, are experimental. They risk failure; they also risk adverse side-effects, most obviously on civil liberties. But around 2.5bn people have now been put on some sort of lockdown during the pandemic (see chart 2). Only a fraction of them have been or will be infected, and thus become immune. The rest, when they emerge, will need watching—for their own sakes, and for the sakes of those around them."