Within weeks, the virus has infected nearly 8,000 people in China and killed 170.
Close to 100 cases have been confirmed in other countries, from Japan to the United States. On Thursday, the World Health Organization declared the outbreak a global emergency.
Statistics from China indicate that just over 2% of people known to be infected with the virus have died, suggesting that it may be less deadly than the coronaviruses behind Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS).
