A staff member checks the information of a passenger entering China at the Pudong International Airport in Shanghai, east China, March 19, 2020. (Xinhua/Ding Ting)

A newly-confirmed imported case of COVID-19 from Kazakhstan, reported on Friday in Jinan of East China's Shandong Province, received four nucleic acid tests, all of which returned negative results, before testing positive, raising concerns over asymptomatic infections and low detection rate on imported cases.

The patient, a resident of Hubei working in Kazakhstan, returned with a negative nucleic acid test result in Kazakhstan before boarding his flight back to China.

Upon arriving in Jinan on August 8, the individual showed no fever or respiratory symptoms, and tested negative in both nucleic acid tests and IgG and IgM antibody tests, local authority said on Friday.

However, the patient's two IgG antibody tests taken later in quarantine returned positive results, proving that he had the coronavirus. The patient also received a nasopharyngeal swab on August 19 test which confirmed the infection.