Coronaviruses are a large family of viruses that typically affect the respiratory tracts of birds and mammals, including humans. Human coronaviruses (CoV) can cause a variety of illnesses ranging from the common cold to more severe diseases such as the Middle East respiratory syndrome and Severe Acute respiratory syndrome, more commonly known as MERS-CoV and SARS-CoV.
The coronavirus is named after its crown-like shape, which is derived from Latin corona, meaning "crown" or "wreath". There are four main sub-groupings of coronaviruses – alpha, beta, gamma, and delta – and seven coronaviruses that can infect people, four strains (229E, NL63, OC43 and HKU1) are typically not severe and three (SARS-CoV, MERS-CoV, and SARS-Cov-2) which can be fatal.
Human coronavirus was first discovered in 1965. Scientists have since found that coronaviruses also infect many types of rodents and domestic animals (eg. mice, rats, dogs, cats, turkeys, horses, pigs and cattle). In some instances, animals can transmit coronaviruses to humans, thus creating novel dangerous coronavirus strains such as SARS-CoV, MERS-CoV, and SARS-Cov-2.
Human coronaviruses vary greatly in severity and risk. The four non-severe strains of Human coronavirus (229E, NL63, OC43 and HKU1) generally produce mild symptoms akin to the common cold. However, they can also cause colds with major symptoms, such as fever and sore throat. The other three strains (MERS-CoV, SARS-CoV, SARS-CoV-2) are potentially more severe, and can cause major respiratory illnesses such as pneumonia and bronchitis.
In 2019, a new deadly coronavirus outbreak was identified in China and quickly spread to other countries. Coronavirus disease 2019, or COVID-19 is caused by the virus SARS-CoV-2, or Severe Acute Respiratory syndrome coronavirus. The origin of SARS-CoV-2 is believed to have an animal origin through spill over, but the quick spread of infection is almost entirely from human-to-human transmission. As of record, the earliest known infection occurred on 17 November 2019 in Wuhan, China.