Cured patients waving goodbye to medical workers before leaving the Leishenshan hospital in Wuhan, central China's Hubei Province, April 4, 2020. On Sunday, 17 coronavirus-infected patients recovered and were discharged from the hospital. (Photo by Gao Xiang/Xinhua)

China does not have a large proportion of asymptomatic patients, and most recovered COVID-19 patients will not infect others, said Zhong Nanshan, a leading respiratory disease specialist.

Asymptomatic patients usually exist in two groups: people from areas where the virus is rife who have not yet shown symptoms after being infected; and those who have had close contact with confirmed cases, said Zhong, during an interview with People's Daily on Sunday.

He stressed that the proportion of those patients is relatively small.

Some asymptomatic patients may show an onset of symptoms later, said Zhong, noting that this group of patients are infectious.

Zhong said he and his team are researching the infectiousness of the second group of virus carriers, noting that based on the virus' particularity, once symptoms show, this group of people possess a strong ability to infect.

The second group of people are now being put under quarantine and observation.

Zhong also said concerns that recovered patients may be infectious do not worry him.

"The so-called 'recovered patients who test positive again' mainly refer to the fact that they tested positive again for nucleic fragments, not that they were invaded again by the virus," Zhong said.

He said attention must be paid to whether the virus invades recovered patients again. If patients already develop strong antibodies inside them, normally they won't become infectious.

Normally, the virus's nucleic fragments are not infectious, said Zhong, noting that scholars cultivated throat swabs from recovered patients and found no virus in them, according to Zhong.

In rare situations, patients who already have underlying diseases only see an improvement in their symptoms but do not recover completely. Zhong said this group of patients are, in fact, infectious.