ABSTRACT
An outbreak of a novel coronavirus disease (COVID-19) caused by the coronavirus (SARS-CoV-2) was first reported in Wuhan, China in December 2019, and soon spread rapidly across the globe causing a deadly pandemic. One of the earliest observations made was that there was a great variation in the susceptibility to infection and mortality rates in different parts of the world. It appeared that general BCG vaccination policies adopted by different countries may influence the transmission patterns, as well as COVID-19-associated morbidity and mortality. Large-scale clinical trials are needed to confirm the non-specific protective effects of BCG. [ FROM AUTHOR] Copyright of Current Science (00113891) is the property of Indian Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full . (Copyright applies to all s.)
ABSTRACT
The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) was first identified in December 2019 in Wuhan, China. Since then, the virus has been rapidly spreading across countries, resulting in the present Corona Virus Disease (COVID-2019) pandemic. Thousands of genomes of different strains of the virus have been sequenced and made available in the public domain which has helped to detect viral mutations and track movement of the virus across the globe. The whole genome sequence of SARS-CoV-2 isolated from a human strain has 96.2% similarity to a bat coronavirus. The strains of SARS-CoV-2 found in different countries are genetically diverse and infections have been shown to be caused by multiple introductions in the same country. Though there are several theories regarding the origin of this virus, genetic studies indicate that it may have appeared by natural selection in humans following zoonotic transfer. This review highlights the recent knowledge of the origin of the coronavirus, its diversity in different geographical regions and mutations, which have aided it to infect the human host.