Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2): A Review on the Origin, Evolution and Emerging Variants

In 2019 the outbreak of the coronavirus disease (COVID-19) was first reported in Wuhan, China, and afterwards spread worldwide. The disease was confirmed to be a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In most cases the human coronaviruses have their origin from animal which are called their natural hosts. The natural hosts of the following Coronaviruses, HCoV-229E, SARS CoV, HCoV-NL63, and MERS-CoV is from bat, while these, HCoV-OC43 and HKU1 may have originated from rodents. The α and β – coronaviruses have their origin and major natural reservoir from Bats. However, several scientific reports validated the hypothesis that the Malayan pangolin might carry a novel Coronavirus that has unique similarity to SARS-CoV-2. SARS-CoV-2 has been observed to continuously change through mutation. Several variants of SARS-CoV-2 with diverse sets of mutations have been detected globally. Several mutations are being monitored while others have been de-escalated because they are extinct or no longer in circulation. Authorized vaccines have been developed against the COVID-19 such as Pfizer-BioNTech and Moderna and these vaccines are mRNA vaccines that penetrates the muscle cells and gives instructions to the cell machinery to produce non-toxic part of S-Protein.