Does living in a healthy county protect you from Coronavirus?

No, the virus is affecting counties in a remarkably similar way.

July 7, 2020

Like me, you might have expected healthier counties in the U.S. to be less affected by the Coronavirus. We know existing medical problems in individuals contribute to the severity of the disease. So, its not unreasonable to guess that same effect would occur in county populations.

How do you measure the health of a county?

I relied on the County Health Rankings Project at University of Wisconsin for guidance. They rank the health of counties within each state using a weighted model of health policies, factors, and outcomes.

University of Wisconsin County Health Model Framework

However, the output from their model are ranks of each county within each state. That presents two problems for nationwide comparison:

  1. Rank differences aren’t necessarily different - e.g. the #1 healthiest county in a state may not actually be significantly healthier than #4.

  2. Since the ranks are done within each state, there is no way to compare the health of counties across states.

To fix this, I created a nation-wide county health index using 50 variables from their model, but skipping their ranks.

Variables used to create a nation-wide county health index

The variables were reduced to two dimensions using Non-Metric Multidimensional Scaling. The first dimension was then scaled from zero to one to create a county health index.

Comparing the effect of Coronavirus vs. the health of a county

One way to look at the effect of Coronavirus in counties is to simply compare the number of cases. However, the number of cases in an area is highly dependent on size of the population. In fact, about 80% of variation in the number of cases in a county can be explained by population size alone.

Coronavirus cases in a county vs. population.

Another way to measure Coronavirus impact is to compare the number of deaths. Here, we have a similar issue - the number of deaths in a county is dependent on the number of cases, and therefore the population.

A measure of Coronavirus impact that removes the population effect is the percentage of cases resulting in death. I used this number to test against the health of counties.

Percentage of Coronavirus cases resulting in death in counties compared to county health index.

There is no real relationship between the effect of Coronavirus and the health of a county. Coronavirus is affecting county populations similarly, regardless of their health. This is also illustrated when mapping Coronavirus effects across the nation.

Map of Coronavirus effect in counties. The size of a point represents the number of Coronavirus cases resulting in death, and the color represents county health index. Counties not shown had no cases as of July 8, 2020

The focus is still on the individual

This analysis reinforces the idea that the effect of the Coronavirus in our country depends on individual action. Living in a healthy place can’t protect us, but taking healthy actions can.

Simple actions proven to prevent both spread and lethality of viruses

More on the Coronavirus

County health data source: University of Wisconsin County Health Rankings Project

Coronavirus data source: USA facts Coronavirus dashboard, retrieved on July 8, 2020

Data and R code available on GitHub

Written on July 9, 2020


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