The spread of the new coronavirus has reached a pandemic, spanning 112 countries and regions, the World Health Organization declared, as disruptions to daily life ricocheted around the world.

The WHO generally defines a pandemic as a disease that has become widespread around the world, with an impact on society. The term has been applied to only a few diseases in history—a deadly flu in 1918, the H1N1 flu in 2009 and HIV/AIDS among them.

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