People leave and enter Wuhan via tollgate

People in Wuhan, once the epicenter of the crisis, are starting to return to work, tracked by a smartphone app that shows if they are symptom free.

Those who live outside but work in the city pass through a toll bridge where they are monitored through the app.

Vehicles with plates showing they belong to areas outside Wuhan are not allowed to pass the toll gate.

First of all, their health is checked through their phones.

The app works through a barcode being scanned - a green code and part of the individual's identity card number appears on the screen.

If the code had been red, that would tell the guard that the individual was confirmed to be infected or had a fever or other symptoms and was awaiting a diagnosis.

A yellow code would mean they had contact with an infected person but hadnt finished a two-week quarantine, meaning they should be in a hospital or quarantined.

Passengers with a green health code have to get off and find their own way to continue the trip inside Wuhan, some have to squeeze into a unlicensed taxi, others are picked up by their employers.

24-year-old Cai Luo, employee of an Internet company, arrived from her hometown Huanggang.

"I had to show my green code and be checked at every stop on the way back," Cai said, "I felt panicked because I had never come across before."

22-year-old Wei Lei, a high speed railway worker, is trying to leave Wuhan to go back to his work at Huangmei County, on the border between Hubei and Jiangxi.

Wei was stopped by a police officer because although he has a green health code, he failed to show an official letter that proves he is healthy and he is needed at his work.

He was told he needs approval from the government of Huangmei County and the village where the high speed railway construction is going on.

"It is very complicated for us to get back to work," said Wei, "Policies and rules keep changing every day."