Coronaviruses are believed to cause 15 to 30% of all common colds in children and adults. Coronaviruses cause colds with major symptoms, such as fever and sore throat from swollen adenoids, primarily in the winter and early spring seasons. Coronaviruses can cause pneumonia and may cause bronchitis.
Figure 1. General symptoms of coronavirus infection.
Coronavirus disease 2019 (COVID-19)
Those infected may either be asymptomatic or develop the most common symptoms including fever, tiredness, and dry cough. Symptoms may appear 2-14 days after exposure. The incubation period ranges from 1 to 14 days with an estimated median incubation period of 5 to 6 days according to the WHO.
Infected people can develop diarrhea, aches and pains or upper respiratory symptoms (e.g. nasal congestion, runny nose, sore throat), although these symptoms are less frequent. These symptoms are usually mild and begin gradually. However, over 80% of the infected people recover from the disease without needing special treatment. Some cases can progress to pneumonia, multi-organ failure, and death in the most vulnerable. Around 16% of infected people becomes seriously ill and develops difficulty breathing. Older people, and those with underlying medical problems like high blood pressure, heart problems or diabetes, are more likely to develop serious illness. Children seem to handle the disease better than adults as the symptoms are usually milder, but sufficient evidence is still lacking.
Figure 2. Symptoms of Coronavirus disease 2019 (COVID-19).
Video 1. Caring for patients with 2019-nCoV. (Source: WHO)
Middle East respiratory syndrome (MERS-CoV)
The clinical spectrum of MERS-CoV infection ranges from no symptoms or mild respiratory symptoms to severe acute respiratory disease and eventually death. A typical presentation of MERS-CoV disease is fever, cough and shortness of breath. Pneumonia, gastrointestinal symptoms, including diarrhoea, have also been reported. Severe illness can cause respiratory failure that requires mechanical ventilation and support in an intensive care unit. The virus appears to cause more severe disease in older people, people with weakened immune systems, and those with chronic diseases such as renal disease, cancer, chronic lung disease, and diabetes.
Approximately 35% of infected people with MERS have died, but this may be an overestimate as mild cases of MERS may be missed by existing surveillance systems.
Severe acute respiratory syndrome (SARS-CoV)
SARS, or severe acute respiratory syndrome, is the disease caused by SARS-CoV. Initial symptoms are flu-like and may include fever, muscle pain, lethargy symptoms, cough, sore throat, and other nonspecific symptoms. The only symptom common to all patients appears to be a fever above 38 °C (100 °F). SARS may eventually lead to shortness of breath and pneumonia. SARS-CoV has a unique pathogenesis because it causes both upper and lower respiratory tract infections.