Coronavirus is a type of single-stranded RNA virus with a lipid bilayer called an envelope on the outside, and it looks like a corona under an electron microscope. It cannot self-regenerate, attaches to and enters human cells via ACE2 receptors, and proliferates within the human cells. There have been some coronaviral diseases such as SARS, MERS and "normal" human coronaviruses (HCoV) that cause common colds. The "new coronavirus" was named as SARS coronavirus-2 (SARS-CoV-2), and new coronavirus infectious disease caused by SARS-CoV-2 was named as COVID-19 short for "corona-virus disease discovered in 2019". SARS-CoV-2 infection spreads before the symptom onset, and prophylactic actions such as wearing masks and social or physical distancing are very important and critical. Treatment of COVID-19 is mainly performed by appropriately combining respiratory management, neutralizing antibody drugs, antiviral drugs, corticosteroids (dexamethasone, prednisolone, etc.), immunomodulators (baricitinib, tocilizumab), anticoagulants (heparin, etc.), and antibacterial drugs, and treatment of comorbidities is also performed in parallel.