Five years ago, a cluster of people in Wuhan, China, fell sick with a virus never before seen in the world.
The germ didn’t have a name, nor did the illness it would cause. It wound up setting off a pandemic that exposed deep inequities in the global health system and reshaped public opinion about how to control deadly emerging viruses.
The virus is still with us, though humanity has built up immunity through vaccinations and infections. It’s less deadly than it was in the pandemic’s early days and it no longer tops the list of leading causes of death. But the virus is evolving, meaning scientists must track it closely.
Where did the SARS-CoV-2 virus come from?