A Chinese health app, developed to enforce the Communist party’s draconian Covid-19 restrictions, is being repurposed to tighten political control on dissidents and others deemed to be troublemakers.

Only the very young and very old are exempt from the compulsory National Health Code System. The ‘traffic light app’, as it has been dubbed, assigns Chinese citizens a colour code: green, yellow or red to signify Covid infection risk. Those with green are free to move around; red can mean instant quarantine. The app requires users to submit information about their health status and other personal details, while at the same time harvesting online behavioural and location data. The precise way people are categorised is far from clear, but the authorities, including public security, have unfettered access. The information is managed by what are described as local ‘big data management bureaus’.

Cities are blanketed with automated code readers – at the entrances to underground stations, offices, malls, apartment blocks, banks and even in taxis. Movement is nigh-on impossible without a green code. Main roads into the southern city of Shenzhen have even been policed by drones hovering above traffic and displaying a QR code which drivers had to scan before being allowed entry.

But it seems that Covid isn’t the only thing that can affect your traffic light status. Earlier this month hundreds of desperate investors, victims of an alleged financial scam, were grounded by the app when they tried to travel to seek redress from a bank that had frozen their money. They had been fighting to get their savings back, but when they tried to reach the bank’s headquarters in Zhengzhou, they received red health warnings on their Covid-19 apps. These investors were then herded into quarantine hotels guarded by police and put on trains home the following day. Others never managed to leave home before getting the red light – even though they lived in Covid-free areas. They had shared their grievances online and had discussed travel plans on China’s heavily monitored social media.

A coincidence? Many in China don’t seem to think so. The plight of the Henan investors has attracted such widespread anger on social media that the party’s usually hyper-vigilant censors have struggled to erase it. One post likened the manipulation of the codes to ‘the plot of a dystopian novel that couldn’t get past the censors’. While another said, ‘Sooner or later, this sort of thing is going to happen to us all. Wake up people’. Even state media weighed in, blaming overzealous local officials. ‘If some officials abuse their position by turning healthy people’s health codes red, they are crossing a dangerous red line,’ said the newspaper China Daily.

Beijing is clearly worried that the outcry will undermine its zero-Covid policy, which is already facing unprecedented internal criticism, by shattering trust in the technology at the heart of it. ‘If speculation of the abuse of power to misuse the health code is allowed to circulate on the internet, it will generate damage to the government’s credibility,’ warned the Global Times, a CCP tabloid.

The action in Henan is not the first time the traffic light app has been used to suppress political dissidents. Late last year, Xie Yang, a Changsha-based human rights lawyer, tried to travel to Shanghai to visit the mother of a citizen journalist who had been jailed for reporting on the initial Covid outbreak in Wuhan. He was stopped at the airport and was thrown into quarantine when his app turned red, flagging him as high risk of the virus. His home city had no cases of the virus at the time. ‘The Chinese Communist party has found the best model for controlling people,’ he said shortly afterwards. In January he was detained and accused of inciting subversion and provoking trouble.

The CCP has already floated the idea of making the app permanent once its seemingly never-ending fight against Covid is over. In Hangzhou, where the traffic light app was pioneered, officials have suggested it become what they call a ‘personal health index’, with everybody required to carry it. The city’s Communist party secretary described the app as an ‘intimate health guardian’, without ever explaining how it would be developed beyond Covid.

China is not the only country where repressive technology has been adopted in the name of fighting a health emergency. The UK government nearly brought in its own vaccine passports – some officials openly praised China’s efforts – before dropping the legislation. Vigilance is needed everywhere to prevent emergency measures from being repurposed and made permanent.

China should serve as a warning, where the concept of good health starts with loyalty to the party. For the country’s deeply paranoid leaders, dissent is the ultimate disease.