From SARS and MERS to COVID-19: a brief summary and comparison of severe acute respiratory infections caused by three highly pathogenic human coronaviruses

Table 1 The phylogenetic origin, crucial events and basic demographic information of SARS-CoV-2, SARS-CoV and MERS-CoV

	SARS-CoV-2[6,7,8,9]	SARS-CoV[10,11,12]	MERS-CoV[13,14,15]
Genus	Clade I, lineage B	Clade I, lineage B	Clade II, lineage C
Length of nucleotides	29.9 kilobases	29.75 kilobases	30.11 kilobases
First emergence	7 December 2019, Wuhan, China	16 November 2002, Foshan, China	4 April 2012, Zarqa, Jordan
Virus identification	January 2020	March 2003	June 2012
Causative agent declaration	January 2020	April 2003	September 2012
Recent status	Pandemic ongoing	Completely control	Sporadic continuous
Number of infected cases	Above 12.7 million^a	8096	2553
Male-to-female ratio	1.27:1	1:1.13	1.78:1
Number of attributed deaths	Above 566 thousand^a	774	876
Number of viral Footprint	213 countries or regions^a	29 countries or regions	27 countries or regions
Case fatal rate	4.4%	9.6%	34.3%

NA Not available. ^a According to the data released by the WTO on 13, July, 2020

ISSN: 1465-993X