Emergence of COVID-19 (formerly 2019-novel Coronavirus): a new threat from China

Coronaviruses cause diseases in birds, mammals, and humans, and were first identified in the mid-1960s (Lee, 2015; Bande et al., 2015; CDC, 2020). These viruses are named for the crown-like spikes on their surface (CDC, 2020). Based on the classification of the International Committee for Taxonomy of Viruses (ICTV) coronaviruses are from order Nidovirales, family Coronaviridae and subfamily Coronavirinae. The viruses contain a positive sense, single-stranded Ribonucleic acid (RNA) genome ranged from 26 to 32 kilobases (kb) in length and thus have the largest genomes for RNA viruses (van Regenmortel et al., 2000). These viruses are further divided into four main subgroups named alpha, beta, gamma, and delta. There are seven human coronaviruses cause infection in humans including 229E (alpha coronavirus), NL63 (alpha coronavirus), OC43 (beta coronavirus), HKU1 (beta coronavirus), Middle East Respiratory Syndrome, or MERS (beta coronavirus), Severe Acute Respiratory Syndrome, or SARS (beta coronavirus), and the newly identified 2019 Novel Coronavirus (2019-nCoV) (CDC, 2020). Common symptoms of the disease include fever, cough, respiratory symptoms, shortness of breath and breathing difficulties (WHO, 2020).