There aren't a large number of asymptomatic patients of COVID-19 pneumonia in China now, a renowned respiratory expert said during an interview with China Central Television on Sunday.

Asymptomatic COVID-19 patients refer to those who do not show any symptoms, including fever and cough, but their tests for the novel coronavirus are positive.

Zhong Nanshan, an academician of the Chinese Academy of Engineering, said the infection rate is usually very high of those who have close contacts with asymptomatic novel coronavirus carriers.

"But the number of confirmed COVID-19 cases is reducing in the mainland, and that indicates China did not have many asymptomatic novel coronavirus carriers," Zhong said.

However, Zhong said he did not have any specific number on China's asymptomatic novel coronavirus carriers and more detailed and professional studies and research are needed in the following months.

At a symposium held in Shanghai on Friday, Zhang Wenhong, leader of the Shanghai team of experts in the treatment of COVID-19 cases, said asymptomatic coronavirus carriers might not show symptoms for more than three weeks and will not be detected if they don't go to hospital for virus tests.

"Those asymptomatic coronavirus carriers usually have strong immunity and show no symptoms for more than two weeks despite being infected. If they return home from abroad and are not isolated timely or released from the two-week quarantine, they will cause great risk of community infection," Zhang said.

"That's the tricky point of the novel coronavirus containment."

Wu Fan, director of the Shanghai Preventive Medicine Association, said the most effective way to prevent oneself from being infected by the asymptomatic coronavirus carriers is to strengthen personal protection.