2. What are the differences between the symptoms caused by COVID-19 and those by SARS, flu, and common cold?

According to the current clinical cases, COVID-19 is mainly manifested by fever, fatigue, dry cough, etc. Some patients may also have upper respiratory tract symptoms such as nasal congestion, runny nose, sputum, and digestive symptoms such as diarrhea. In some cases, the disease aggravates after one week, symptoms of pneumonia such as dyspnea, and other complications appear. Mild infections show only low fever, mild fatigue, and no pneumonia. Some virus-carriers have no obvious clinical symptoms, even though they test positive for SARS-CoV-2 in nucleic acid detections.

The symptoms of severe cases caused by COVID-19 are similar to that of SARS.

The main symptoms of flu (abbreviation for influenza) are fever, cough, headache, sore throat, myalgia or arthralgia, whole body malaise, etc., body temperature can reach 39-40°C, accompanied by chills, loss of appetite, dry cough, stuffy nose, runny nose, and retrosternal discomfort. Some patients have mainly gastrointestinal symptoms such as vomiting, abdominal pain and diarrhea. The course of disease for patients without complications is self-curing. The fever gradually subsides after three to four days, and other symptoms improves, although it usually takes one to two weeks before the cough disappears and physical strength recovers. The most common complication of influenza is pneumonia.

The symptoms of the common cold are stuffy nose, runny nose, fever, etc. Most patients have mild symptoms and usually no pneumonia.