Table 2.

Qualitative behaviour of symptoms of COVID-19 vs. cold and influenza (flu): Tentative histogram by symptom (“feature”/“variable”) in ternary quantification [from no/low (“+”) to frequent/high (“+ + +”)].

Symptom	COVID-19	Influenza	Cold
Breathing: Dypnea (Shortness)	+ + +	++	+
Breathing: Difficulty	+ + +	++	+
Rhinorrhea (Running nose)	+	++	+ + +
Nasal congestion	+	+	+ + +
Coughing	dry ++	dry ++	+
Sneezing	+	+	+ + +
Sore throat	+	++	+ + +
Pain: Body	+	+ + +	++
Pain: Head (Headache)	++	+ + +	+
Fatigue, Tiredness	mild ++	+ + +	+
Appetite loss	+	+ + +	+
Onset gradient	+	+ + +	+

Shown is also the symptom gradient onset behaviour. Further frequently related variables include behaviour and personality changes, diarrhoea, fever, sore tongue, or watery eyes, which could partially be assessed also by audio—the latter two rather by physiological and visual sensors, respectively. Assembled from diverse references, the table is indicative in nature on purpose, and more fine-grained quantification could apply.