China’s scientists are looking for a way out of the zero-covid policy

NOT SINCE the early days of the pandemic has China seen so many new, locally transmitted cases of covid-19. More than 400 were reported on March 9th (counting only those that were symptomatic). Clusters have been found in most of China’s provinces (see map). A surge of this size would not trouble most countries. Indeed, many are learning to live with the virus. But in China the new cases are testing the government’s “zero-covid” strategy, which uses mass testing and lockdowns to crush any hint of an outbreak.