(Yicai Global) July 29 -- Nanjing ordered all its 9.3 million residents to be tested for the novel coronavirus for the third time yesterday as the city in eastern Jiangsu province struggles to contain an outbreak of the highly contagious Delta strain that started 10 days ago.

Another 18 cases of Covid-19 were detected today, bringing the total to 171 since a number of workers at the Nanjing Lukou International Airport were found to be infected on July 20. Of these, 78 cases are mild cases, 86 are showing normal symptoms, seven are severely ill and two are asymptomatic, the municipal government said.

The outbreak is likely to have spread further as at least seven other cities have reported cases among people who recently visited Nanjing, a major commercial and transportation hub.

Testing extends late into the night.

A medical worker in a hazmat suit swabs the back of the throat of an elderly lady.

Residents line up to be tested. The banner reminds them to keep a distance of one meter from each other.

Editors: Tang Shihua, Kim Taylor