On December 31, 2019 China has alerted World Health Organization (WHO) to several cases of pneumonia of unknown aetiology in Wuhan city in central China. On January 7, a novel coronavirus was identified from the throat swab sample from a patient and its originally abbreviated as 2019-nCoV by WHO. Coronavirus study group later renamed this pathogen as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and WHO named this disease as coronavirus disease – 2019 (COVID-19).

SARS-CoV-2 is a member of family Coronaviridae and order of Nidovirales. The Coronaviridae family viruses are sub divided into four groups namely (a) Alphacoronavirus, (b) Betacoronavirus, (c) Gammacoronavirus and (d) Deltacoronavirus. Phylogentic analysis revealed that SARS-CoV-2 is closely associated (with 88% identity) with two bat-derived SARS-like coronaviruses. The SARS-CoV-2 uses angiotensin-converting enzyme 2 (ACE2) as the receptor as that for SARS-CoV and it is mainly spread through respiratory tract.As of April 27, 2020, totally 2,810,325 people are affected with COVID-19 and 193,825 confirmed deaths have been recorded by WHO. Globally, 213 countries have been affected with SARS-CoV-2.