The CDC issued a report summarizing coronavirus disease in the United States from January 22nd through May 30th. (CDC Report) The report covers over 1.3 million cases. The median age of an infected person was 48 years old. Incidence per 100,000 people was lowest among children age 9 and under at 51.1 (.05%). In interestingly it rose to 541.6 (.54%) among 40-49 year-olds and 550.5 (.55%) among 50-59 year-olds before dropping to 478.4 (.48%) among 60-69 year-olds and 464.2 (.46%) among 70 to 79 year-olds, then rising again to 902 (.9%) among those 80 and over. This suggests two things, one is that the working age population has many more contacts or opportunities for infections than do older groups, and the second is that if you are over 80, even with limited contacts you have a high risk of infection. Older people likely get infected with exposure to a far lower dose than do younger and middle-aged persons. The incidence among men and women was relatively equal. Hispanics and African-Americans have a higher incidence rate than their proportion of the population, but other research indicates this is likely exclusively due to higher prevalence of pre-existing conditions that may be linked to risk.
A little over 20% of the included cases had information on other health conditions. The most common were cardiovascular disease, diabetes and chronic lung disease. Older persons were obviously more likely to have pre-existing health issues. Complete data on characteristics of hospitalizations, ICU use and deaths were not available for even half the cases, but in aggregate, 14% of patients were hospitalized, 2% ended up in the ICU and 5% died. Hospitalizations were 6 times more likely for patients with pre-existing conditions and deaths were 12 times more likely. Although their case rates were similar, males were more likely to be hospitalized, need ICU or die. Hospitalization and death rates were very high for those over 70. I don’t think anyone can dispute at this point that this is just an extraordinarily bifurcated epidemic, with the general population at very low risk for serious illness and the elderly at very high risk.