How severe is COVID-19? What exactly is the difference between COVID-19 and the flu? Some people say it's just a strong flu, so we don't need to worry about that?

Bruce Aylward: No, this is a virus you have to worry about. It is not a flu virus, but a coronavirus. It will not mutate as fast as the flu virus and change its properties. And this virus has already told us it is a virus that can kill. It can kill many people, especially older people, people with comorbid diseases, as we call them, or other conditions. But it can also kill young people. People have to remember that. We understand that if people have conditions such as cardiovascular disease they're at a higher risk. But there are other things. And people don't understand why. And I spoke to a lot of doctors in China about this.

I said, "What do you really think is going on?" And they said that in the young ones they didn't quite know. And that's concerning, as well. So this is a virus that can kill between 1 percent and 4 percent of the people who get affected. That is a lot for a virus that can spread so easily. So you have to take this seriously. Flu, seasonal flu, is less than 1 percent. A fraction of 1 percent of the people who get it may die. This is an order of magnitude different.

Bruce Aylward, a Canadian epidemiologist and leader of the WHO-China Joint Mission on COVID-19, shares his insights with China Daily in Geneva on March 6.