Coronavirus disease 2019 (COVID-19) was caused by a novel type of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It was originated in Wuhan, China in December 2019. It spreads rapidly all over the world since respiratory virus infection can occur through many easy ways (e.g. contact, droplet spray, aerosol) and besides, asymptomatic people also have contagiousness. So far, there have been 23,491,520 confirmed cases of COVID-19, including 809,970 deaths, reported to World Health Organization (WHO), which declared it as a significant threat to global health. Fever, fatigue, and dry cough are the commonly observed symptoms in the patients. In COVID-19, the main affected system is respiratory system and some cases demonstrate a rapid progression to acute respiratory distress syndrome (ARDS), while other organs are less involved. Angiotensin-converting enzyme 2 receptor-virus association is essential and responsible for the development of the disease. SARS-CoV-2 causes deaths through its severe effects on the respiratory system.