# US county study of 2,745 variables: poverty share correlates with COVID-19 excess deaths, CC +0.64

- Published: 2026-11-12 09:56 UTC
- Section: Life & Health › Medicine
- Tags: COVID-19 excess deaths, US county analysis, poverty and mortality, Area Health Resources File, socioeconomic determinants of health, health system capacity, age-standardized mortality, Pearson correlation, Frontiers in Public Health
- URL: https://realtech.media/news/rt-f59840508f14a107fdd3345d_us_county_study/

**An ecological analysis of US counties found socioeconomic and demographic factors tied to excess deaths more strongly than health system supply, mainly in 2020–2021.**

![US county study of 2,745 variables: poverty share correlates with COVID-19 excess deaths, CC +0.64](https://realtech.media/media/2026/11/03dcaf06d480d54e.jpg)
*MDWiki (from Our World In Data), Wikimedia Commons, CC BY 4.0*

A team including John P. A. Ioannidis of Stanford University School of Medicine reported a county-level analysis of COVID-19-era excess mortality in the US. The paper was published in Frontiers in Public Health on 11 November 2026 (doi.org). The authors screened 2,745 pre-pandemic county variables against age-standardized excess deaths for each year from 2020 to 2024. [1]

## Data and method

The variables came from the raw Area Health Resources File rather than from pre-built composite indices. They cover demography, race and ethnicity, income, insurance, education, employment, housing and health systems. For each variable the authors kept the most recent pre-pandemic value, with a median reference year of 2018. [1]

The authors calculated Pearson correlation coefficients (CC) with population-weighted county excess deaths. They grouped the variables into 11 semantic super-clusters. [1]

## Strongest correlations

Overall, 24.1% of variables reached at least a moderate correlation (|CC| > 0.30), and 7.4% reached a strong one (|CC| > 0.45). The strongest were poverty share (CC +0.64), college attainment (−0.62) and high income (−0.61). [1]

The share of variables with at least moderate correlations was 11.4% in 2020 and 14.8% in 2021. It fell to 3.3% in 2022, 1.3% in 2023 and 4.1% in 2024. The concentration in 2020–2021 was sharpest in the population under 65. [1]

Of 656 variables with |CC| > 0.30, 295 of 454 in the moderate band and 200 of 202 in the strong band belonged to demographic and socioeconomic super-clusters. Only 10% of health system variables reached |CC| > 0.30, compared with 42% of socioeconomic and demographic variables. [1]

## Robustness and limits

The authors tested other choices: the latest available value up to 2023 or 2015, different population weighting, and Spearman correlations. The direction and the leading variables stayed unchanged. The correlation magnitudes scaled with the weight given to large counties. [1]

The analyses are ecological, so they describe associations between county-level characteristics and excess deaths. According to the authors, the results suggest stronger relationships of socioeconomic structure and demographics with excess mortality than of baseline health system structure and supply, especially in 2020–2021. [1]

## Sources

1. [doi.org](https://doi.org/10.3389/fpubh.2026.1975691)
2. [bioengineer.org](https://bioengineer.org/socioeconomic-factors-strongly-correlated-with-us-covid-19-county-excess-deaths)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-f59840508f14a107fdd3345d_us_county_study/