Over the past week, their Lunar New Year absence prolonged by the coronavirus outbreak, Chinese people have been gradually returning to work. As they prepare to leave their hometowns, they can, or are sometimes obliged to, provide personal data such as recent travel and health conditions on their smartphones, usually through Alibaba and Tencent's apps.

Based on their responses, algorithms will show a health code colored green, yellow or red, signifying the likelihood that they have coronavirus and thus their fitness to join millions of others on the road in China. Those who get a red code must either self-quarantine or be quarantined in a facility for 14 days.

Lying is out of the question. All the information provided, including their recent whereabouts, hotel stays or travels, is cross-checked with government big data ranging from smartphone location data to ID-linked train ticket purchases.

Another powerful tool deters lying: China's social credit system. At least one province and some cities are factoring lies into people's social credit scores, which measure citizens' trustworthiness based on data ranging from smoking on trains to jaywalking. More local governments are likely to follow.

This comprehensive effort is the latest sign that Beijing's all-seeing digital network is strengthening. The fight against the COVID-19 outbreak is demonstrating how efficient this airtight data system can be, but also how terrifying. If it is successfully fighting a virus, imagine how effective it could be in combating mass protests, small gatherings and the individual pursuit of justice.

To be sure, anti-outbreak measures, aided by technology, are necessary, efficient and smart. Compared with dozens of trips to government agencies to acquire a travel clearance, the simplicity of acquiring a colored health code significantly reduces crowd flow and cross-infections.

Deployment of the colored health code is trying to outrun the spread of the virus. As of February 19, over 10 million people in Hangzhou had been assigned their health code and the tech has rapidly spread to nearly 200 cities across the country.

In Shanghai, an app monitors its 245,000 street-front shops with self-reported data, eliminating the need for government staff to visit thousands of shops daily. When the virus is finally contained, we will see that technology was a major supporting factor.

While it is difficult to answer the question of how to balance public health against individual privacy and rights in a health emergency, the COVID-19 outbreak exposes troubling aspects of the Chinese surveillance network.

This has, in a matter of decades, become so deep, so wide and so interconnected that it is almost impossible for anyone to escape its grip. While the Chinese population tolerates Beijing's far-reaching digital tentacles, international condemnation has not slowed China's pace in furthering its capability.

There is little transparency regarding how the Chinese government collects and cross-checks data, but a low-level official in Jiaxing city in Zhejiang province offered an insight. On a local government news website, Deng Hui said about the health code, "Through data analysis, we have mastered the trajectory of everyone's whereabouts. If you have not reported truthfully, our system will find out."

He illustrated the extent of the penetration of the Chinese government's data network. With the help of artificial intelligence, the accuracy which the system can reach in pinning down one person's behavior is even greater.

This powerful digital cage has been built gradually. Requiring real ID to register mobile phone numbers and internet services; installing hundreds of millions of surveillance cameras on the streets; utilizing big data and AI to auto-generate intelligence: the all-seeing state is closing in.

Commuters walk by surveillance cameras at a subway station in Beijing, pictured in February 2019: the all-seeing state is closing in. © AP

With the coronavirus crisis, the process of incorporating individuals' health data into this powerful network will surely be accelerated. In Hangzhou, the government has upgraded the health code to link it to a person's digital health card, similar to a digital medical record, and social security card, allowing one to make doctor's appointments, purchase medicine and make payments.

These are worthy initiatives, yet we must be mindful that walls between data are breaking down in other spheres at the same time. As a Chinese person living in China, you must assume that the government knows everything about you: where you travel; what you eat; who you argue with online; and how you commented about now-deceased coronavirus whistle-blowing doctor Li Wenliang.

Once this digital network is constructed, there is no dismantling it. Aside from lamenting its moral challenges, we must face its consequences. This cyber tool at the disposal of Beijing means the Chinese system now has even better means for overcoming problems that in any previous decade might have meant the end of a regime.

Nina Xiang is the founder of China Money Network, a media platform tracking China's venture and tech sectors. She is also the author of "Red AI: Victories and Warnings From China's Rise In Artificial Intelligence."