s A Recent Update on SARS-CoV-2 Transmission and its Variants: Transmission, Pathogenic Mechanism, and Treatment

Coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 virus was first reported in China. As of April 17, 2022, over 500 million confirmed cases and over 6 million deaths have been reported worldwide. COVID-19 is transmitted through respiratory droplets and other contact routes in the human community. Fine respiratory droplets and aerosol particles enter into the respiratory tract and come in the contact with mucous membranes. The SARS-CoV-2-containing droplets spread into the environment by quiet breathing, speaking, exercise, coughing, and sneezing of COVID-19-infected individuals. World Health Organization (WHO) have been released several guidelines for controlling COVID-19 which include maintaining personal hygiene, social distance, and COVID-19 vaccination. A higher transmission rate of SARS-CoV-2 has been reported and the transmission rate also depends on several variants of SARS-CoV-2. SARS-CoV-2 genome is a single-stranded positive (+) sense RNA of about 26- 32 kb nucleotides and has 80% similarity to the bat SARS-CoV. SARS-CoV-2 enters the host cell through the interaction between spike proteins of the virus and the host cell surface receptor. Acute Respiratory Distress Syndrome and lung injury lead to the death of SARS-CoV-2-infected people. Several vaccines for COVID-19 have been developed, giving protection from COVID-19 and reducing the transmission rate. Developed vaccines are not 100% effective against SARS-CoV-2 due to variations in the genetic makeup of SARS-CoV-2. Thereby, further research is the need of the hour. This review summarizes SARS-CoV-2 and its several variants and their transmission, genomic characterization, pathogenhost interaction mechanisms, diagnostic methods, and potential treatment approach for SARS-CoV-2.