Aerial view of university students lining up to get nucleic acid tests in Xi’an, capital of Northwest China’s Shaanxi province, on Tuesday. The city, home to 13 million people, has recorded a total of 234 cases since Dec. 9. Photo: VCG

Two ambulances drive on a road on Thursday in Xi’an. Photo: VCG

A resident registers his personal information at the gate of a community in Yanta district in Xi’an Thursday. All districts and communities of the city have put in place stringent control measures from Thursday. Photo: VCG

Citizens in Xi’an purchase daily necessities at a shopping mall on Wednesday before the implementation of closed management of communities. Photo: VCG

An epidemic prevention and control worker sprays disinfectant at a community in Yanta district of Xi’an on Dec. 16, which was closed off after a resident was found to be positive. Photo: VCG

A disinfection vehicle sprays disinfectant on a road in Yanta district in Xi’an on Dec. 16. Photo: VCG

A child takes nucleic acid test at a testing site in Yanta district in Xi’an on Dec. 16. Photo: VCG

Medical staff collect swab samples from the students of Xi’an Technical University for nucleic acid testing on Tuesday. Photo: VCG

Medical staff work in a gas membrane laboratory for nucleic acid testing on Wednesday in Xi’an, with a maximum daily capacity of 250,000 tests. Photo: Zhang Yuan, China News Service/VCG

Residents of a community in Xi’an line up overnight for nucleic acid tests on Saturday. Photo: VCG

Citizens line up to get nucleic acid tests in Xi’an on Tuesday. Photo: Zhang Yuan, China News Agency/VCG

The Dayan Tower, a famous tourist site in Xi’an, is temperately closed on Monday due to the epidemic prevention and control requirements. Photo: VCG