Table 1.

Comparison of Different Types, Clinical manifestation, Incubation period, and incidence of Corona variants.

Types of corona variant	Subgroup	Clinical manifestation	Incubation Period	Year	Incidence	References
HCoV-229E	Alpha-coronavirus	General malaise, headache, nasal discharge, sneezing, sore throat, fever, and cough.	2–5 days	1966	N/A	[47], [189], [190]
HCoVOC43	Beta-coronavirus	General malaise, headache, nasal discharge, sneezing, sore throat, fever, and cough.	2–5 days	1967	N/A	[191], [192]
HCoV-NL63	Alpha-coronavirus	Mild respiratory disease is similar to the common cold, cough, rhinorrhea, tachypnea, fever, hypoxia, obstructive laryngitis (croup).	2–4 days	2004	N/A	[193], [194], [195]
HCoV-HKU1	Beta-coronavirus	Upper respiratory tract fever, running nose, and cough lower respiratory tract, fever, productive cough, and dyspnea.	2–4 days	2005	N/A	[196], [197]
Severe acute respiratory syndrome coronavirus (SARS-CoV).	Beta-coronavirus	Fever > 37.8 °C (100,0°F), chills, headache, malaise, myalgia, lethargy, sore throat, pneumonia (direct viral or secondary bacterial), non-productive cough, dyspnea, respiratory distress, Diarrhea (30–40% of patients).	2–14 days	2003	9% died, much higher for those over 60 years old, with mortality rates approaching 50% for this subset of patients	[198]
Middle East respiratory syndrome coronavirus	Beta-coronavirus	A severe respiratory illness characterized by fever, cough dyspnea, chills, sore throat, myalgia, arthralgia, pneumonia, diarrhea and vomiting (one-third of patients), acute renal impairment.	2–13 days	2012	The case fatality rate is 35–40%	[134], [199], [200], [201], [202]
Novel coronavirus COVID-19	Beta- coronavirus	Asymptomatic, mild infection: fever, dry cough, malaise, dehydration.Severe infection: high fever, shortness of breath, chest pain, hemoptysis	2–14 days	2019	~ 468,644 cases (Dec 2019 – March 2020)	[203], [204], [205]