The city of Zhengzhou ordered its nearly 13 million residents to take Covid-19 tests on January 5 after a handful of cases were reported, as China fights to stamp out virus clusters ahead of the Beijing Winter Olympics.

Everyone in the Henan provincial capital, which has been placed under a partial lockdown, must be tested to “thoroughly uncover infections hidden among the public”, the city’s government said in a statement on January 5.

The city has reported 11 cases in recent days.

State media said about 500 close contacts had been traced from the outbreak’s two symptomatic cases, linked through mahjong rooms and family gatherings.

The mass-testing order came as case numbers in the locked-down city of Xi’an fell to their lowest in weeks, with officials saying that outbreak had been “brought under control”.

Xi’an’s 13 million residents have been under stay-at-home orders for the last fortnight.

China has stuck to a rigid approach of stamping out Covid cases when they appear, with tight border restrictions and targeted lockdowns since the virus was first detected in the country in 2019.

China recorded 91 cases on January 5 – including 35 in Xi’an, the city’s lowest tally since mid-December.