Coronavirus disease is caused by a virus that is part of a large family of viruses - coronaviruses (CoV). It has been known to cause common respiratory infections ranging from common diseases like the common cold to more critical illness such as severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). However, the coronavirus disease-causing virus (COVID-19) is a new strain of the coronaviruses that was discovered in 2019, which has never been previously identified in humans.

Coronaviruses (CoV) are known to be zoonotic - that is, they are usually transmitted between humans and animals. Several investigations proved that SARS was transmitted to humans from civet cats, and MERS was also transmitted from dromedary camels to humans. There are still several strains of coronaviruses known in animals that are yet to infect humans.

Coronaviruses got their name from the resemblance of the spikes protruding from their surface with a crown and the sun’s corona. They infect humans and animals, thereby causing illness in the respiratory tracts. Every year, there are at least four different strains of the coronaviruses that cause mild infections such as the common cold. Most people will get infected with at least one of these viruses at some point in their lives.