PMC:7079563 / 9206-10842
Annnotations
2.1 Human coronaviruses
Human coronaviruses (CoVs) could cause respiratory, gastrointestinal, hepatic and central nervous system diseases. Infection outcomes vary from mild, self-limiting disease, to more severe manifestations and even death [1,11]. Among the seven human CoVs, two α-coronaviruses (HCoV-229E and HCoV-NL63) and two β-coronaviruses (HCoV-OC43 and HCoV-HKU1) were thought to cause only mild self-limiting upper respiratory disease, such as common cold in immunocompetent hosts, except for a few cases of severe infections in infants, children and seniors [12,13]; the other three CoVs could cause fatal respiratory diseases. In 2002, the Severe acute respiratory syndrome coronavirus (SARS-CoV) emerged in Guangdong province, China, spreading to 37 countries, and its subsequent global epidemic was associated with 8096 cases and 774 deaths. Ten years later, Middle-East respiratory syndrome coronavirus (MERS-CoV) spread to 27 countries, causing 2494 infected cases and 858 deaths worldwide [1]. And the recently identified novel coronavirus (2019-nCoV), was the third highly pathogenic CoV discovered, with a mortality of 2% which is much lower than that of SARS-CoV (10%) and MERS-CoV (37%) [6]. However, the transmissibility of 2019-nCoV is higher, the mean R0 (R0 is used to estimate the transmissibility of virus) of 2019-nCoV ranged from 3.3 to 5.5, and it appeared (slightly) higher than those of SARS-CoV (2–5) and MERS-CoV (2.7–3.9) [[14], [15], [16]]. Measures on ‘entry, exit and travel’ screening and restrictions are likely to reduce the effective R0, which should benefit 2019-nCoV control and prevention.