Table 1.

A brief summary and comparison of three highly pathogenic human coronaviruses (severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus (MERS-CoV) and coronavirus disease 2019 (COVID-19)) on the basis of their phylogenetic origin, basic demographic information, and associated events

Pandemics	SARS-CoV	MERS-CoV	COVID-19	References
Place of origin	Foshan, Guangdong, China	Saudi Arabia	Wuhan, Hubei, Province, China	(da Costa et al. 2020)
Date of emergence	Nov 2002	June 2012	December 2019	(da Costa et al. 2020)
Entry receptor in human	Angiotensin-converting enzyme 2 (ACE-2)	Dipeptidyl peptidase-4 (DPP4)	(ACE-2)	(Lu et al. 2020) (Wang et al. 2008) (Li et al. 2020)
Mode of transmission	Droplet contacts with the infected individual	Respiratory droplets, contaminated fomites	Droplet contact with an infected individual (even if asymptotic one), aerosol transmission, blood-borne transmission, child-mother, and sexual transmission contaminated fomites, oral-fecal	(Shashank et al. 2021, Karia et al. 2020)
Incubation period	4 days (~ 1–13 days)	5 days (~ 2–15 days)	5 days (2–14 days)	–
Countries and territories affected	29	27	268	(Al-Qahtani 2020)
Current status	Completely controlled	–	Ongoing pandemic	–
Fatality ratio	9.5%	34.4%	4.4%	(Petrosillo et al. 2020)