Covid Is Spreading In Unexplained Ways, Dimming Containment Hope

New York, 16 July 2020:

As countries across Asia Pacific struggle with resurgences of the COVID-19, 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.

“You can hardly contain the outbreak because you have no idea where they will come out next,” said Yang Gonghuan, former deputy director general of China’s Center for Disease Control and Prevention. “When there’s more cases where the origins are unknown, it adds to the difficulty for containment.”

In contrast, a low share of cases of unknown origins means that authorities can stay relatively relaxed -- like in South Korea and Japan -- even if total daily new infections reach the hundreds. These countries can take a targeted and nimble approach, shutting down schools or workplaces where clusters are found, but allowing the rest of the population to live normally.

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. Here’s a breakdown of how the places fighting flareups are using the number to guide their responses: Bloomberg