COVID-19 compared to other epidemic coronavirus diseases and the flu

Table 1 Comparison of severe acute respiratory syndrome coronavirus, Middle East respiratory syndrome coronavirus and severe acute respiratory syndrome coronavirus2

	Severe acute respiratory syndrome (SARS-CoV)	Middle East respiratory syndrome (MERS-CoV)	Severe acute respiratory syndrome (SARS-CoV2)
Classification[5]	Beta coronavirus	Beta coronavirus	Beta coronavirus
Country of onset[4,5,7]	First reported in November 2002 in the Guangdong province, China	First reported in April 2012 in Saudi Arabia	First reported in December 2019 in Wuhan, China
Origin[2,4]	From bats, which infected civets and then humans	From dromedary camels to humans	Believed to have spread from contact with bats
Global spread[5,8]	29 countries worldwide	27 countries worldwide	185 countries and territories worldwide as of April 12, 2020 (ongoing)
Timeline[4,5,7]	Last case in 2004	Last case in 2019	Ongoing (as of May 7, 2020)
Cases and fatalities[5,8]	It infected 8098 persons and resulted in 774 deaths	It infected 2494 persons and resulted in 858 deaths	About than 3,836,215 cases and 268,999 deaths as of May 7, 2020
Transmission[5]	Droplets/contact	Droplets/contact	Droplets/contact
	In addition, it is possible that these viruses might be spread more broadly through the air (airborne spread) especially during an aerosol generating medical procedures.
Incubation period[5]	Typically, 2-7 d or up to 10-14 d in some cases	2-14 d	1-14 d
Symptoms[3]	Fever, non-productive cough, sore throat, headache, myalgia, malaise, shortness of breath, chest pain, vomiting, and pneumonia	Fever, severe acute respiratory illness, cough, and shortness of breath, and pneumonia	Fever, cough, headache, body weakness and myalgia (fatigue), shortness of breath, and breathing difficulties. In severe cases, individuals may show symptoms of pneumonia
CFR[4,5,8]	9.6%	34.4%	2.2% (initial reports)
Treatment[4]	There are no antiviral drugs effective against coronaviruses. Supportive treatment using corticosteroids (methylprednisolone) to reduce lung injury induced by inflammation has been used to reduced acute respiratory distress
Vaccines[4]	There is no approved and marketed vaccine against SARS-CoV, MERS-CoV, or SARS-CoV-2

SARS-CoV: Severe acute respiratory syndrome coronavirus; MERS-CoV: Middle East respiratory syndrome coronavirus; CFR: Case fatality Rate; The ratio of deaths from a disease to the total number of people diagnosed with this disease for a certain period of time.

Table 2 Comparison of coronavirus disease 2019 and the flu

Factors	COVID-19	Flu
Incubation period	2-14 d	1-4 d
Symptoms[3]	The most common symptoms are cough, sore throat, headache, body weakness and myalgia (fatigue) due to severe respiratory illnesses associated with shortness of breath and breathing difficulties. In severe cases, individuals may show symptoms of pneumonia	Typical flu symptom is characterized by a sudden onset of fever, cough (usually dry), headache, muscle and joint pain, severe malaise (feeling unwell), sore throat and a runny nose
Case fatality rate[8,20]	Initial reports from China suggest the case fatality rate is at least 2.2% (unresolved), and United States 3.9% as of April 12, 2020	The case fatality rate for the flu in the United States is < 0.1%
Virus transmission[17,21]	The basic reproduction number, R0 is about 3.2	The production number of the flu is about 1.28
Characteristic	Pandemic	Endemic, potential for epidemic or pandemic
Prevention[19,22]	There is no approved vaccine for COVID-19	There is an annual flu vaccine

COVID-19: Coronavirus disease 2019; R₀: the average number of people who catch the virus from a single infected person.