An overview of the structure SARS-CoV-2 virus and its method of replication in the body
Throughout history, infectious diseases have been the major cause of morbidity and mortality across countries. Emerging and re-emerging infectious diseases have been a major concern within the recent past. According to the World Health Organization (WHO), over thirty new infectious agents have emerged worldwide in the past three decades, out of which 60 percent are of zoonotic origin and have accounted for 26 percent of annual deaths worldwide. Several viral epidemics such as the severe acute respiratory syndrome coronavirus (SARS-CoV) in 2003, H1N1 influenza in 2009, and Middle East respiratory syndrome coronavirus (MERS-CoV) in 2012 took a heavy toll of life and had a considerable impact on social, economic, and public health systems worldwide. In December 2019, a cluster of cases of unexplained acute pneumonia was reported from Wuhan City of China’s Hubei province. These initial cases were classified as “pneumonia of unknown etiology” as the causative agent could not be ascertained. Later on, the etiology of this illness was attributed to a novel virus belonging to the Coronaviridae family and was designated as 2019-nCoV by the WHO. On January 30, 2020, as per the International Health Regulations (IHR, 2005), the outbreak was declared as a Public Health Emergency of International Concern (PHEIC) as it had spread to 18 countries with four countries reporting human-to-human transmission. On Feb 11, 2020, the WHO renamed the disease as coronavirus disease 2019 (COVID-19). The same day, the Coronavirus Study Group (CSG) of the International Committee on Taxonomy of Viruses designated 2019-nCoV as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on the basis of a phylogenetic analysis of related coronaviruses. Considering its contagiousness and potential to evolve into a pandemic, the WHO upgraded the threat alarm to the “very high” level on February 28, 2020. With the dismal increase in the number of COVID-19 cases outside China, affecting more than 118,000 people across 114 countries and over 4,000 deaths, the WHO declared COVID-19 a pandemic on March 11, 2020. COVID-19 has emerged has one of the worst pandemics in human history with a staggering number of more than 100 million affected people across 216 countries and territories with more than 2 million deaths as of January, 2021.COVID-19 is a respiratory illness with a clinical spectrum comprising mild to moderate disease (80%), severe disease (15%), and critical illness (5%) with an overall case fatality rate of 0.5–2.8%. The severe and critical illness categories (about 20% of all infections) have overwhelmed the healthcare systems worldwide.