As Covid-19 Surges, the Big Unknown Is Where People Are Getting Infected – The Wall Street Journal

Western nations face a big challenge in fighting the Covid-19 pandemic: Ten months into the health crisis, they still know little about where people are catching the virus.

The problem is becoming more acute as new cases are breaking records in the U.S. and Europe and pressure grows on authorities to impose targeted restrictions on places that are spreading the virus, rather than broad confinement measures that are wreaking havoc on the economy.

In…