In December 2019, the World Health Organization was alerted to several cases of pneumonia in Wuhan, China. The virus responsible for the disease did not match any other known virus. On January 7, 2020, China confirmed that a new virus from the coronavirus family had been identified that was responsible for this new disease called COVID‑19.

Some viruses in the coronavirus family cause disease in animals, while others cause disease in humans. Coronaviruses that cause disease in humans can be spread by close contact between people. In rare cases, coronaviruses that infect animals can also infect people. Like SARS‑CoV‑2, the virus responsible for COVID‑19, two other coronaviruses are spread from animals to humans and cause or have caused serious disease in humans, namely, SARS‑CoV in 2003 and MERS‑CoV since 2012