SARS (severe acute respiratory syndrome) Overview. Severe acute respiratory syndrome (SARS) is caused by the SARS coronavirus, known as SARS CoV. Coronaviruses are common viruses linked to infections in humans and animals. There are several recognised human coronaviruses that cause mild respiratory infections, such as the common cold. However, this type of virus can also include strains that cause more severe illnesses, such as SARS. There have been two self-limiting SARS outbreaks to date, during 2002 to 2004 (see below) associated with a highly contagious and potentially life-threatening form of pneumonia.