Death rates. Here are the updated, officially counted covid deaths per 100K population by race/ethnicity in the United States:

• Overall = 61 deaths per 100K
• White = 39 deaths per 100K
• Black = 93 deaths per 100K
• Hispanic = 60 deaths per 100K

Fatality as lagging indicator of infection. Official death counts probably underestimate the number of fatalities attributable to covid infection. However, the cumulative death rate is the most accurate indicator of the population’s infection rate. Using the IHME’s estimated US covid fatality rate of 0.85% for the US , here are the imputed cumulative infection rates by race/ethnicity:

• Overall = 61/(.0085 x 1000) = 7.2 percent infected
• White = 39/(.0085 x 1000) = 4.5 percent infected
• Black = 93/(.0085 x 1000) = 10.9 percent infected
• Hispanic = 60/(.0085 x 1000) = 7.1 percent infected

Age adjusted fatality rates. The 0.85% fatality rate estimate is an overall average for the US population. Age, however, is a significant predictor of covid mortality; e.g., per the CDC, 65-74 year olds infected with covid are 90 times more likely to die of the disease than are infected 18-29 year olds. All else equal, populations with a higher median age will have a higher mortality rate. Here is median age by race/ethnicity of the US subpopulations:

• Overall = 38 years
• White = 44 years
• Black = 34 years
• Hispanic = 30 years

Based on the CDC’s data, as well as national seroprevalence studies conducted in various countries, each additional year of population median age results in about a 10% higher mortality rate. Conversely, younger populations have a 10% per year lower mortality rate compared to the overall average. The year-by-year age adjustments are geometric rather than linear, compounded annually. So, calculating the age-adjusted covid fatality rates by race/ethnicity:

• Overall = 0.85% fatality rate
• White = 0.85% x 1.1⁶) = 1.51% age-adjusted fatality rate = 1.78 times the overall rate
• Black = .0085/1.1⁴ = 0.58% age-adjusted fatality rate = 0.68 times the overall rate
• Hispanic = .0085/1.1⁸ = 0.40% age-adjusted fatality rate = 0.47 times the overall rate

Age-adjusted infection rates. Combine these intermediate calculations to arrive at cumulative US age-adjusted covid infection rates by race and ethnicity:

• • Overall = 7.2 percent infected
  • White = 4.5/1.78 = 2.5 percent infected
  • Black = 10.9/0.68 = 16.0 percent infected
  • Hispanic = 7.1/0.47 = 15.1 percent infected

In this series of posts I’ve chronicled my own learning about the coronavirus pandemic, focusing in particular on estimating the prevalence of the virus especially in the US population. My schooling and professional background gave me a head start on this exploration; my demographic vulnerability and my curiosity have motivated me to persist.

It’s possible that readers of these posts could have come away not only with the results of my investigations, but also with a battery of methods and resources for conducting their own analyses. It’s also possible that, having written these posts, I could organize what I’ve learned and how I learned it into a class for teaching others — call it Applied Epidemiology: Covid. There wouldn’t be many lectures, nor would there be many assigned background readings. Instead, the class would consist mostly of a series of projects, progressing from simple to complex. The work would be cumulative, with knowledge and skills and resources acquired in earlier projects being brought to bear on subsequent projects.

Here’s a project that would be ideal for this hypothetical Applied Epidemiology class.

The Canadian government just released summary findings from a nationwide covid seroprevalence survey. The assignment: evaluate this survey.

The article includes both descriptive and evaluative material, giving the student a head start. But anyone who’d have taken this class would have developed hands-on competence in using a variety of other evaluative criteria and resources that go beyond the article.