Unlike the Trump administration, which has said it is prioritizing opening the economy while essentially giving up on controlling the pandemic, China moved aggressively to stop the virus. The result: China’s economy is growing and life there is returning to a semblance of normal, while the United States is struggling with a third wave of infections and the prospect of new restrictions. Economic growth in China has surged, hitting 4.9 percent in the latest quarter, and consumer spending has slowly started to recover. Residents are once again flocking into malls, bars, concert halls and hair salons, while schools, subways and offices are crowded. China has effectively sealed off its borders from the outside world and doubled down on efforts to eradicate the virus. When a crop of cases emerge, the government swiftly shuts down vast areas and quickly tests millions of people, to help keep local transmissions near zero.