At the invitation of Chinese Ambassador to South Korea Xing Haiming, China's top respiratory expert Zhong Nanshan and South Korean health experts exchanged experiences in containing the spread of COVID-19 via a webinar on Friday afternoon, with topics including asymptomatic cases, imported cases and the trend of the global pandemic.

Most asymptomatic cases are infectious

The asymptomatically infected people actually involve two groups, one comprises people who have come into contact with COVID-19 patients, the other involves travelers from places with severe outbreaks, said Zhong. When they are infected, they have the virus in their upper respiratory tract.

Currently, most of the infected appear to be infectious as many asymptomatic people will develop symptoms over a period of time. However, some preliminary studies show a very small number of people whose nucleic acid test is positive but who don't have any symptoms over a long time. It is unclear whether they are contagious.

"We prefer to treat the asymptomatically infected people as potentially infectious ones and isolate them appropriately. It's safer," said Zhong, adding that the proportion of these cases now is very small.

China has issued a circular on the management of asymptomatic cases of COVID-19 to strengthen the detection, reporting and treatment of such cases.

Pandemic trend depends more on 'intervention'

The trend of the global COVID-19 pandemic depends on two aspects. One is the law of the disease itself, and the other is intervention, according to Zhong.

"Now this disease has mutated to be well adapted to survive in the human body," the expert said. It spreads vigorously and has a much higher mortality rate than flu, estimated by the World Health Organization to be 10 times higher.

The law of disease refers to mutation and development rules. For general respiratory diseases, they will decrease in the summer.

And "intervention is a more important aspect," said Zhong.

The high mortality rate of COVID-19, which in some European countries even reached 10 percent, requires rapid development of a vaccine. That's a way of human intervention, while "herd immunity" won't work as it requires a huge sacrifice.

"The state of the pandemic also relies greatly on the attitude of European and American governments," stressed Zhong. "None of the countries on the Earth can stay out of the battle. The whole world cannot be at ease when the outbreak takes place in any one county."

He called for joint cooperation among governments, saying the key to the pandemic is containing and reducing the infection.

Vigilance but no discrimination regarding imported cases

For the imported cases, Zhong said, "As long as we take rigorous measures, including strict tracing, quarantine once detected, and close observation of those people who came into contact with COVID-19 patients, the outbreak won't take place."

Zhong added that it's not realistic to clear all imported cases, but they can be kept to a minimum level.

Regarding racist remarks online, Zhong emphasized that the infection does not target at a certain race and there's no racial difference when facing the disease.

"Once infected, people should be treated equally to get medical treatment and isolated. There should not be any racial discrimination."