China's virus epicentre pivots to stem imported cases

The ground-zero city of Wuhan is cautiously reopening after a two-month quarantine, but the birthplace of the global coronavirus pandemic is now on guard against a potential new threat: imported cases.

Travel restrictions have been loosened, with Wuhan's busy train station officially resuming inbound services on Saturday and highways reopened as the unprecedented lockdown that kept more than 50 million people across Hubei province housebound is lifted.

That has unleashed a reverse tide of local residents who were stranded elsewhere in China -- where many reported facing ostracism or restrictions on their movements -- and are now flocking back to homes they have not seen for at least 10 weeks.

The returnees -- many arriving by train wearing two face masks, latex gloves and protective suits -- bring with them the potential for a new round of infections, and authorities are taking few chances.

Before leaving Wuhan's station, all passengers are required to register their personal details and travel history before proceeding through temperature checks.

They also must show either a certificate of good health or a "green" rating -- for "safe" -- on a mobile phone app system that has been adopted nationwide and uses big data to track whether a person visited any high-risk areas in China. Without that, travellers must submit to a nucleic acid test for the virus, an official