Epidemiology: Mapping COVID-19 disease burden across the USA

Per capita COVID-19 disease burden and healthcare system demand may be highest in rural areas in the USA, according to a modeling study published in Nature Medicine. These findings underscore the importance of ensuring that access to medical care and public-health resources are available to communities outside of urban areas.

Identifying regions of the USA in which the number of COVID-19 cases is highest is crucial for the distribution of emergency medical services and public-health resources during the pandemic.

Ian Miller and colleagues used age-specific mortality patterns along with demographic data to map the cumulative case burden of COVID-19 and the subsequent burden on healthcare resources across the USA. The authors developed a modified susceptible-exposed-infected-recovered epidemiological model and performed the analysis on 3,142 counties and county equivalents under a scenario in which 20% of the population of each county acquires infection. They identified counties that are likely to be consistently more heavily affected than the rest of the country across a range of assumptions about transmission patterns, such as basic disease reproductive rate, contact patterns and efficacy of quarantine. The authors found several regions in need of additional support, including much of the western part of the USA, the northern Midwest, Florida and northern New England. Since age is associated with disease severity, the areas with the highest per capita burden were those with the highest percentages of people over the age of 60 years.

Future research is needed to consider how other factors linked with an increase in disease risk — such as pre-existing health conditions, societal factors or decreased access to medical care — might exacerbate disease burden in certain regions. The authors urge public-health officials to carefully consider patterns of relative burdens rather than projections for individual counties when planning emergency responses.