About 80% of patients have mild to moderate disease (including non-pneumonia and pneumonia cases), 13.8% have severe disease and 6.1% are critical (respiratory failure, septic shock, and/or multiple organ dysfunction/failure). Individuals at highest risk for severe disease and death are people aged over 60 years of age and those with underlying conditions such as hypertension, diabetes, cardiovascular disease, chronic respiratory disease and cancer. Disease in children appears to be relatively rare and mild. About 2.4% of the total reported cases were individuals under 19 years of age. A very small proportion of those aged under 19 years have developed severe (2.5%) or critical disease (0.2%).
But the virus’s destructive potential has overshadowed one encouraging aspect of this outbreak: So far, about 82 percent of the cases — including all 14 in the United States — have been mild, with symptoms that require little or no medical intervention. And that proportion may be an undercount.