With the World Health Organization (WHO) declaring a global health emergency over the coronavirus outbreak in China, governments around the world are frantically trying to put in place measures to stem the spread of the disease that has already made its presence felt in 18 countries.

The epidemic, which originated from Wuhan, the capital of China's Hubei province, has killed more than 200 people and infected more than 9,000. Sian Griffiths, an emeritus professor at the Chinese University of HK, explains what the WHO declaration means in practical terms.