The World Health Organization raised its global risk assessment of the new coronavirus to its highest level after the epidemic spread to sub-Saharan Africa and financial markets slumped.
The virus has proliferated around the globe over the past week, emerging on every continent except Antarctica, prompting many governments and businesses to try to stop people from travelling or gathering in crowded places.
It has killed more than 2,800 people and infected over 84,000 worldwide - the vast majority in China - since it emerged apparently from an animal market in the central Chinese city of Wuhan in late December.
But it is its rapid spread to new zones that has authorities concerned - in the past 24 hours, it has affected nine new countries, from Azerbaijan to Mexico to New Zealand.
New drastic measures were put in place: Switzerland cancelled all gatherings of more than 1,000 people, and Saudi Arabia banned Gulf citizens from its holy cities of Mecca and Medina.
Those efforts come as the number of deaths and new infections has been tapering off in China, following unprecedented quarantine efforts locking down tens of millions of people in the worst-hit cities.
But infections elsewhere have started to surge, with Iran, Italy and South Korea becoming the major new hotspots and cases being confirmed in around 50 countries
The WHO has voiced particular concern about Africa's preparedness, warning that the continent's health care systems were ill-equipped to respond to a COVID-19 epidemic.
In Iran, unnamed health system sources said that at least 210 people had died of the coronavirus - far beyond the official death toll of 34.