CORONAVIRUS | Smooth sewage flow in drainage system is critical to the control of the novel coronavirus (Covid-19) outbreak, according to China's leading respiratory expert Zhong Nanshan on Tuesday.

As human-to-human transmission continues in the central Chinese city of Wuhan, the centre of the epidemic, Zhong urged medical workers to take thorough protective measures and residents to pay attention to the drainage system.

"Because we have incubated live virus from faeces, we hope news outlets can tell the public that smooth sewage flow in the drainage system is critical to reducing infection. 

"Overseas experts and I agree that people do not get infected by eating food with the virus, but by breathing in aerosol from contaminated faeces which still has the virus in dry condition. So hospitals should also pay attention to this problem," Zhong said.

In response to cases with an incubation period of over 14 days, Zhong said the 14 days are the median incubation period of the virus and it is common to find exceptions.

"Only one out of 1,099 researched cases has an incubation period of 24 days, but we must record it honestly. Only 13 of these cases see an incubation period of over 14 days. You must consider both the majority and the minority. 

"For example, the incubation period of rabies can be as long as half a year. So it (14 days) is just an average length of time. It is so in most scenarios. So I do not feel surprised about the exception," he said.

As some people said the accuracy of nucleic acid tests is as low as 30-50 percent, Zhong said such a statement is one-sided.

"The method itself is correct, but you must consider how the samples are collected. In most cases, we collect samples from the nose and pharynx. This is a meticulous process and you must consider whether the samples are properly collected. I think we should believe the nucleic acid test. 

"If we can train more nurses in sample collection, then we can get better samples," Zhong said.

- CCTV+