Table 2 Clinical features of SARS, MERS, and COVID-19

1. Predominant features were constant fever, chill or rigors, dry cough, myalgia, headache, and malaise [50].

1.Onset of disease with fever, chills or rigors, cough, sore throat, myalgia, and arthralgia, followed by dyspnea [51, 52].

1. Predominant symptoms are fever, cough, and sore throat. Other common features are fatigue, myalgia, and dyspnea [53, 54].

2. Less common features were sore throat, running nose, sputum production, dyspnea, anorexia, nausea and vomiting, headache, and dizziness [50, 55].

2. Enteric manifestations such as diarrhea, vomiting, anorexia, and stomach pain [56, 57].

2. Unusual features such as headache, nausea or vomiting hemoptysis, and diarrhea [1, 25].

3. Severe cases: recurrence of fever, shortness of breath, hypoxemia, and ARDS [58].

3.Severe patients: ARDS, multiple organ failure including renal failure and respiratory failure [59, 60].

3. Severe patients: acute pneumonia, hypoxemia, and ARDS [28].

4. Almost 61% manifested mild symptoms, 11.1% had acute respiratory complications [27].

4. 21% of patients exhibited mild or no symptoms, whereas 46% possess severe complications or died [61].

4. 80.9% of patients had mild pneumonia, 13.8% had acute complications, and 4.7% considered critical and needed ICU care [62].