The latest data on COVID-19 cases and fatalities from the Centers for Disease Control and Prevention (CDC) confirm that young people face a negligible risk of dying from the disease, while people 65 and older face a much higher risk. Patients 65 or older account for about 16 percent of confirmed cases but four-fifths of COVID-19 deaths.
The crude case fatality rate indicated by the CDC's numbers (deaths divided by confirmed cases) is about 0.25 percent for patients younger than 50 and nearly 16 percent—63 times higher—for patients older than 64. While the overall crude CFR is 3 percent, the rates among adults range from 0.07 percent for patients in their late teens and 20s to 29 percent for patients 85 or older—more than 400 times higher. (The fatality rates are even lower among minors: 0.04 percent for children 4 or younger and 0.02 percent for 5-to-17-year-olds.)
Because these calculations include only confirmed cases, the percentages are higher than the fatality rates among all Americans infected by the COVID-19 virus, many of whom never seek testing because their symptoms are mild or nonexistent. Judging from the CDC's antibody studies, the infection fatality rate varies widely from one part of the country to another—from 0.1 percent in Utah to 1.4 percent in Connecticut, for example.
The nationwide infection fatality rate remains unclear, since it depends on how many infections have been undetected. The CDC's current "best estimate," based on studies from around the world, is 0.65 percent, more than twice as high as its implied estimate in May. Since the CDC's antibody research suggests the ratio of total infections to confirmed cases is something like 10 to 1, the earlier estimate may prove closer to the mark.
The strong correlation between age and fatality risk is probably largely a function of preexisting medical conditions, which are more common among older Americans. As of August 22, the CDC reports, 94 percent of COVID-19 fatalities involved "additional conditions or causes"—2.6 on average. Aside from conditions, such as pneumonia and respiratory failure, that may have been caused by COVID-19, the most common comorbidities were circulatory diseases. Hypertension, for example, was noted in more than a fifth of the cases. Diabetes was mentioned 16 percent of the time.
The CDC considers diabetes a risk factor for severe COVID-19, and it lists hypertension as a possible risk factor. Other risk factors mentioned by the CDC include kidney disease, which was noted in 8.5 percent of the deaths; heart failure (6.5 percent); cancer (4.6 percent); and obesity (3.5 percent).
These data reinforce the point that COVID-19 (unlike, say, the "Spanish flu" of 1918) is mainly a threat to the elderly and people with serious preexisting conditions—two groups that overlap a lot. The policy implications depend on which approach to protecting those vulnerable groups makes more sense: broad restrictions that seek to reduce the spread of the virus and thereby make it less likely that high-risk individuals will encounter carriers, or narrower safeguards that aim to shield those individuals until a vaccine or natural herd immunity reduces the danger to a tolerable level.