Once you are exposed to COVID-19, the incubation period - meaning the time between contact with the virus and onset of symptoms - is thought to be up to 14 days. Most people show symptoms within the first 5 days.
According to studies, the symptoms can vary greatly, as can the severity of the disease. Pneumonia appears to be the most frequent serious development caused by COVID-19. This manifests as a fever, cough, shortness of breath and characteristics findings on chest x-ray.
According to the Chinese Centre for Disease Control and Prevention Report:
81% of cases are mild (no or mild pneumonia)
14% of cases were severe (requiring medical attention and/or hospitalization)
5% of cases were critical (requiring admission to the intensive care unit)
Some patients with initially mild symptoms may progress over the course of a week. In Chinese studies, pneumonia developed after an average of 5-8 days and hospitalization was required after 7-10 days from symptom onset.
In people with severe disease, Acute Respiratory Distress Syndrome (ARDS) is a major complication. This is most commonly associated with underlying health conditions. Individuals who progress to ARDS may require breathing assistance such as supplemental oxygen or ventilation.
According to the WHO, recovery time is approximately two weeks for mild infections and 3-6 weeks for severe disease.