The government is using big data to make sure citizens are symptom-free WUHAN: Since the coronavirus outbreak, life in China is ruled by a green symbol on a smartphone screen. Green is the “health code” that says a user is symptom-free and is required to board a subway, check into a hotel or enter Wuhan, the city of 11 million people where the pandemic began in December. The system is made possible by the Chinese public’s almost universal adoption of smartphones and the ruling Communist Party’s embrace of “big data” to extend its surveillance and control over society. Walking into a Wuhan subway station, Wu Shenghong, a manager for a clothing manufacturer, uses her smartphone to scan a barcode on a poster that triggers her health code app. A green code and part of her identity card number appear on the screen. A guard wearing a mask and goggles waves her through. If the code had been red, that would tell the guard that Wu was confirmed to be infected or had a fever or other symptoms and was awaiting a diagnosis. A yellow code would mean she had contact with an infected person but had not finished a two-week quarantine, meaning she should be in a hospital or quarantined at home. People with red or yellow codes “are definitely not running around outside,” said Wu, 51. “I feel safe.” Intensive use of the health code is part of the efforts by authorities to revive China’s economy while preventing a spike in infections as workers stream back into factories, offices and shops. Most access to Wuhan, the manufacturing hub of central China, was suspended on Jan. 23 to fight the coronavirus. The lockdown spread to surrounding cities in Hubei province and people nationwide were ordered to stay home in the most intensive anti-disease controls ever imposed. The final travel controls on Wuhan are due to be lifted April 8. Other governments should consider adopting Chinese-style “digital contact tracing,” Oxford University researchers recommended in a report published in the journal Science. The virus is spreading too rapidly for traditional methods to track infections “but could be controlled if this process was faster, more efficient and happened at scale,” the researchers wrote. Once aboard the subway, Wu and other commuters use their smartphones to scan a code that records the number of the car that they ride in case authorities need to find them later. An attendant carries a banner reading “Please wear a mask throughout your trip. Do not get close to others. Scan the code before you get off the train.” Seats are marked with dots denoting where passengers are to sit to stay far enough away from each other. Visitors to shopping malls, offices buildings and other public places in Wuhan undergo a similar routine. They show their health codes and guards in masks and gloves check them for fever before they are allowed in. The health codes add to a steadily growing matrix of high-tech monitoring that tracks what China’s citizens do in public, online and at work: Millions of video cameras blanket streets from major cities to small towns. Censors monitor activity on the Internet and social media. State-owned telecom carriers can trace where mobile phone customers go. A vast, computerized system popularly known as social credit is intended to enforce obedience to official rules. People with too many demerits for violations, ranging from committing felonies to littering, can be blocked from buying plane tickets, getting loans, obtaining government jobs or leaving the country.