Officials have ruled out the possibility of domestic transmission as the origin of the COVID-19 infections in the northeastern Chinese city of Dalian, said Zhao Zuowei, director of the municipal health commission on Monday.

The genome sequencing of collected samples suggest a difference in genome sequencing from other domestic transmissions, Zhao noted. 

The working presumption is that it was caused by items imported from overseas, said Zhao.

As for now, the efforts in tracing the origin of the virus is still underway, he added. 

A new cluster of infections hit Dalian since a 58-year-old man working with Dalian Kaiyang World Seafood Co. Ltd. tested positive for COVID-19 on July 22.

Dalian has reported a total of 87 confirmed cases of COVID-19 as of Monday morning, among them, 38 patients are link to the seafood company.