This week, the World Health Organization (WHO) upgraded the COVID-19 outbreak to a "pandemic", saying Europe was now at the heart of the problem. 

More than 1,400 people have died from COVID-19 in Italy, meaning it has a fatality rate of about 6.8 percent, the highest in the world. 

We invited Professor Wu Zhiwei, director of the Center for Public Health Research at Nanjing University's Medical School, to give his opinion.