BCG Vaccine, A Ray of Hope in Treating Severe Acute Respiratory Syndrome (SARS).

In December 2019 in China, the Severe Acute Respiratory Syndrome - Corona Virus - 2 (SARS-CoV-2) (also 2019 nCoV) was first discovered. Later, WHO declared that SARS-CoV-2 was responsible for Coronavirus Disease 2019 (COVID-19). The round, elliptical or pleomorphic shape of the 2019-nCoV is 60-140 nm in diameter. It comprises a single stranded genome of RNA that comprises 29891 nucleotides, a lipid shell and spike protein, envelops membrane, and hemagglutinin- esterase (HE) proteins. Several therapeutic approaches have been proposed to combat this disease as this disease became global pandemic. Bacillus Calmette-Guérin (BCG) vaccine could be another approach and at present, it is the only TB prevention vaccine approved. Both TB and COVID-19 cause severe pneumonia. In this review, we have tried to correlate the pathophysiology of both these disease condition. In this review, we also have shown the history and current BCG practice throughout the world and it is hypothesized that the countries which strictly maintained and made mandatory call to recommend BCG vaccination are relatively less affected by COVID-19 pandemic. When BCG is exposed to a subsequent viral infection, it is allowed to lead to cross-reactive T cell responses, which result in increased activity of Cluster of differentiation (CD) 4 + and Cluster of differentiation (CD) 8 + T cells and this may be a ray of hope in treating the SARS infection.