As China lifts its coronavirus lockdowns, authorities are using a color-coded health system to dictate where citizens can go. Here's how it works.

Many cities have imposed strict lockdown measures, with rail and road links severely restricted or completely shut off, to avoid further spread of the coronavirus.

The city of Wuhan, which has been under an intense lockdown since January 23, plans to lift restrictions on April 8.

The rest of Hubei province, where Wuhan is the capital, has already allowing travel again.

As of the end of 2019, WeChat and Weixin — its Chinese version — had 1.16 billion monthly active users.

Alipay has about 900 million users across China, according to The New York Times.

This means the apps are providing the technology and access to the health programs, but local governments are creating the database and issuing the health codes.

The initiative was first piloted in the eastern city of Hangzhou. Authorities there first launched a "health code program" on a government website, and later embedded it into the Alipay app being used by people in the area, the Financial Times reported.

Shortly afterwards the municipal government of Beijing followed suit, integrating the health code program into area users' WeChat apps.

The apps can still perform their normal functions.

A red code means you are either have the coronavirus, had a fever or other symptoms, are still waiting for a diagnosis.

Yellow means you've had contact with another infected person, but haven't finished your two-week quarantine.

Source: Associated Press, The New York Times

Source: Associated Press

Effectively, the app is required now to do anything in many places. Here's what it looks like trying to get onto the subway in Hangzhou. Overnight the city went from lockdown to relying on the app. If your code is green, you can ride. If you're given yellow or red, you're stuck. pic.twitter.com/rettbnhbWW

Source: Associated Press

Source: Ant Financial

An Ant Financial representative did not respond to Business Insider's request for clarification.

Source: Reuters, Financial Times

"We've seen the use of big data to predictive policing and detain people really for no reason," human rights adviser at Amnesty International, William Nee, told Reuters.

"So there's a concern that although this data is being perhaps collected for a legitimate purpose, that it could potentially and eventually be misused in ways that we can't predict right now."

Referring to the app, New York Times reporter Paul Mozur tweeted: "The color codes, checkpoints, and phone searches all smack of policies carried out in Xinjiang. People in China's east aren't used to it."

Read more about how experts think about China's coronavirus surveillance here.

A representative for Ant Financial, which operates Alipay, told Business Insider in a statement:

"We believe digital technology can and should play an active role in helping contain the global spread of the COVID-19 outbreak.

"Ant Financial requires that all third-party developers, including those who offer health code services using our technology platform, strictly adhere to our data security and privacy requirements, which include obtaining user consent before providing services."

Tencent and Alibaba, which part-owns Ant Financial, also said that the government health software hosted on their platforms are required to ask for user permission to access their locations, the Financial Times reported.

Wu Shenghong, who lives in Wuhan, told the Associated Press that the system reassures her that people who are not considered healthy "are definitely not running around outside. I feel safe."

An unnamed Shanghai resident also told Reuters in mid-March: "It's my first time to come outside after the epidemic. But I already used the QR codes several times and I think it's good."