The Real Virus Number Determining If Cities Return to Lockdown

• As countries across Asia Pacific struggle with resurgences of the coronavirus, one data point is steering government responses: the share of cases with no clear indication of how infection occurred.
• These patients cannot be linked to other confirmed infections or existing outbreaks by virus responders, indicating hidden chains of transmission. A growing proportion of such cases in a city’s resurgence pushes governments, like in Australia and Hong Kong, to take broad and blunt action, returning entire cities to lockdown-like conditions.
• This data point is a telltale sign of whether resurgences across the world will flare up into bigger waves, and if residents need to gird themselves for a return to lockdown.
• The Asian financial hub enjoyed three months of normal life before a surprise resurgence this month that looks to set to be its worst wave ever. Infections of “unknown origins” have surged to half of all new local cases, indicating that they are emerging from all corners.

(Source: Bloomberg)