People in China are using apps on mobile phones to follow and perhaps help slow the spread of the new coronavirus, COVID-19. Some of the apps provide the latest information about areas hit by the virus, while others collect data on infected persons. The Chinese government is working with two of the country’s largest technology companies to keep track of the disease. The two, Alibaba Group and Tencent Holdings, created color-based systems that record the health of individuals and identify carriers of the coronavirus. Last week, Alipay, a payment app operated by Alibaba, released a system that uses colored QR Codes to show the health of people in the city of Hangzhou. A QR code is a sign a smartphone can read with its camera. Once the sign is recognized, the phone takes the user directly to an internet link with information about a subject.