ref:https://www.nbcnews.com/health/health-news/covid-flu-rsv-symptoms-comparison-chart-rcna58523

Is it Covid-19, Flu, or RSV?

Three respiratory illnesses are circulating this winter. Here are the symptoms for each.

Signs and symptoms	RSV	Flu	Covid-19
Symptom onset	Gradual	Sudden	Gradual
Muscle and body aches	Sometimes	Common	Sometimes
Cough	Common	Common	Common
Diarrhea	Rare	Sometimes*	Sometimes
Fatigue	Sometimes	Common	Common
Fever	Sometimes	Common	Common
Loss of taste or smell	Rare	Rare	Sometimes
Shortness of breath or difficulty breathing	Sometimes**	Rare	Common
Runny or stuffy nose	Common	Common	Common
Sneezing	Sometimes	Sometimes	Sometimes
Sore throat	Sometimes	Sometimes	Common
Headache	Sometimes	Common	Common

ref:https://www.nytimes.com/2022/12/13/well/covid-flu-rsv-symptoms.html?te=1&nl=virus-briefing&emc=edit_cb_20221214

There is overlap among the symptoms of cold, flu, Covid and R.S.V.

Mark your symptoms below and then sort by selecting an illness.

Illness symptons

Symptoms	Cold	Flu	Covid-19	R.S.V.
Cough	Often	Often	Often	Often
Difficulty breathing	Rarely	Rarely	Often	Sometimes
Fatigue	Sometimes	Often	Often	Rarely
Fever	Rarely	Often	Sometimes	Sometimes
Headaches	Sometimes	Often	Often	Sometimes
Muscle pain or body aches	Sometimes	Often	Sometimes	Rarely
New loss of taste or smell*	Rarely	Rarely	Sometimes	Rarely
Runny or stuffy nose	Often	Sometimes	Sometimes	Often
Sneezing	Often	Sometimes	Sometimes	Sometimes
Sore throat	Often	Sometimes	Often	Rarely
Vomiting or diarrhea	Rarely	Sometimes	Sometimes	Rarely
Wheezing	Rarely	Rarely	Rarely