Coronaviruses are a diverse group of viruses infecting many different animals. They can cause mild to severe respiratory infections in humans. In 2002 and 2012 respectively, two highly pathogenic coronaviruses of zoonotic origin, severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV), appeared in humans and caused fatal respiratory disease, making emerging coronaviruses a new public health issue in the 21st century. At the end of 2019, a new coronavirus designated Severe Acute Respiratory Syndrome 2 (SARS-CoV-2) appeared in the city of Wuhan, China, causing an unusual outbreak of viral pneumonia. Being highly transmissible, this new coronavirus disease, also known as coronavirus disease 2019 (COVID-19), spread rapidly around the world. It has far surpassed SARS and MERS in terms of both the number of people infected and the spatial extent of epidemic areas.