9 cases were detected at a hospital in Qingdao. So China immediately isolated them and contact traced a few levels down and tested all of those. Then tested another 3M people. And plan to test all 9M in the general area by the end of the week.
The kind of efficiency, national organization and seriousness of purpose Americans can hardly imagine.
These are the first known cases of domestic transmission in 2 months, and the minor August outbreak was on the fringe of China out in far west Xinjiang, out by the border with Kazakhstan and other central Asian lands. This was the first reported/confirmed domestic transmission in the main populated part of China in nearly 4 months.
One major concern with this new outbreak follows a week long double holiday from Oct. 1 - 8 which meant that a lot of domestic tourists came to Qingdao and returned home. Shanghai's tourist areas were pretty packed and Qingdao is a pleasant coastal city, one of the few Chinese cities that isn't overcrowded. So that holiday in- and outflux complicates contact tracing with the possibility of long distance transmission.