Shanghai Pudong International Airport enforces stringent measures to prevent the rise of imported coronavirus cases. Photo: Yang Hui/GT

Experts from the Chinese Center for Diseases Prevention and Control (Chinese CDC) said asymptomatic COVID-19 infections will not cause further spreading, although the duration of its virus detoxification is longer than that of SARS.

Wu Zunyou, an expert from the Chinese CDC, said at a Tuesday press briefing that asymptomatic infections are close contacts of COVID-19 patients who tested positive through laboratory diagnostic methods during their isolation. Some remain asymptomatic until the end of the observation period, while others are sent to hospitals once symptoms appear. 

According to Wu, the Chinese CDC says asymptomatic COVID-19 infections will not cause the spread of the virus in society as they are all close contacts and under strict isolation.

Wu noted the key at present lies in carefully observing Wuhan patients discharged from hospitals and conducting epidemiological investigation into imported cases.

China has set up three defensive lines to combat imported coronavirus, including border checks, 14-day quarantine and medical institutions. Most of the imported cases are stopped by the first two defensive lines, and no patient has so far been found in the third line, said Wu. 

However, he said knowledge of COVID-19 is still limited, and Chinese experts are researching the virus through extensive clinical observation and scientific experiments. 

Experts told media that the pathogenicity of COVID-19 is heavier than flu, lighter than SARS, and the duration of virus detoxification is longer than SARS.

Wang Guiqiang, an infectious disease specialist from Peking University, said on Tuesday that the bodies of 29 patients who died of COVID-19 have been dissected, and the coronavirus was still found to be present in them. In addition, the coronavirus' damage to the immune system is a key factor in a patient's death.