One month later: These maps show how quickly Covid engulfed the US again

Updated 1437 GMT (2237 HKT) August 11, 2021

(CNN)More than 98% of US residents now live in an area where there is a "high" or "substantial" risk of Covid-19 community transmission, up from 19% of residents only a month ago. This sharp turn has been driven in large part by the highly infectious Delta variant and low vaccination rates in many regions.

The Centers for Disease Control and Prevention (CDC) measures community transmission using two metrics -- the number of cases per 100,000 people and the test positivity rate, both measured over the previous seven days.
The latest figures from the CDC show an alarming rise in the number of counties that are considered at high risk of community transmission. On Monday, 2,361 counties in the United States were listed in the "high" tier, a stark increase from 457 counties in the same tier at the beginning of July. A look at the past five weeks shows just how rapidly community transmission has increased across the country.