Though genomic sequences of the severe acute respiratory syndrome, or SARS virus, and the novel coronavirus share about 78 percent of similarity, there are differences between the two viruses and two diseases in mortality rates, transmission and pathology, a medical expert said on Wednesday at a news conference in Central China's Wuhan.

The mortality rate of SARS, which remains at about 10 percent, is higher than that of the COVID-19, said Cao Bin, vice-president of the China-Japan Friendship Hospital in Beijing.

"If we look at the cases outside Hubei province, the mortality is less than 1 percent. Even if we look at the mortality in Hubei, the number is about 3 to 4 percent," he said, adding that COVID-19 is less severe than SARS.

However, he stressed COVID-19 is easily transmitted, based on documented cases of the two diseases.

"The new virus is more successful," he said. "COVID-19 is more widely distributed around the world," he said, given the rapid increase of confirmed cases in South Korea, Italy and Iran.

The pathology and mechanism of the diseases show that the new virus can easily invade other organs, including the heart and liver, which adds risks to human beings, according to Cao.

Li Haichao, vice-president of Peking University First Hospital, experienced SARS as a doctor at a hospital in a Beijing suburb with 124 patient beds and six ICU beds in 2003.

Most COVID-19 patients are above 60 years old, while there were many young people in the ward during the SARS period, Li said.

Some older COVID-19 patients showed severe symptoms because they had hypoxemia and severe Acute Respiratory Distress Syndromeand needed a long period of noninvasive ventilation, he added.

Li noted that slow onset is another characteristic of COVID-19. Some patients with mild symptoms, like coughing, became worse 10 days or two weeks later. "The onset is slow but the exacerbation is quick," he said.

"It's really important to take care of patients with hypoxemia because you don't know when and how the situation can be exacerbated, so you must keep close observation on the symptoms," Li explained.