Evaluating the impact of altitudinal variations on COVID-19 mortality rates: a comprehensive analysis

High altitude, known for its effects on respiratory diseases, was analyzed for its potential protective role. Data from the New York Times COVID-19 repository, U.S. Census Bureau, and topographic maps were utilized, covering January 2020 to August 2022, including pre- and post-vaccination periods. This study investigates the influence of high altitude on COVID-19 mortality, fatality rates, and vaccination outcomes in the United States. COVID-19, caused by SARS-CoV-2, has shown significant disparities in severity and outcomes across populations.

This study utilized publicly available data from the New York Times COVID-19 repository and the US Census Bureau's American Community Survey to analyze case fatality rates across mainland US counties from January 21, 2020, to August 13, 2022. Average altitude data were obtained from topographic maps, and counties outside the mainland USA were excluded. Vaccination-related data were assessed using the cutoff date of December 14, 2020. The rural-urban status of counties was determined using the Index of Relative Rurality (IRR) from Waldorf and Kim's study, which included 3105 of 3109 counties.

Counties above 1500 m exhibited significantly lower case numbers, deaths, cases per million, and fatality rates compared to counties below this altitude. Pre-vaccination fatality rates were notably reduced in high-altitude regions (p = 0.0001), while post-vaccination data continued to demonstrate lower fatality rates (p < 0.0001). A positive correlation between rurality and post-vaccination fatality rates was observed (rho = 0.176, p = 0.0001). Altitude, alongside vaccination status, was identified as a critical factor influencing fatality rates (p = 0.001 for both). Additionally, a significant positive correlation between rurality (Index of Relative Rurality) and post-vaccination fatality rates was observed (rho = 0.176, p = 0.0001).

Our findings highlight that high-altitude adaptations, such as increased lung capacity and epigenetic changes, may mitigate COVID-19 severity. However, the role of environmental and genetic factors remains insufficiently explored. Importantly, the study underscores healthcare inequities in rural high-altitude areas, where limited vaccination access exacerbates mortality risks. While altitude shows promise as a protective factor, addressing healthcare access disparities and further investigating high-altitude physiological and genetic adaptations are imperative for optimizing COVID-19 outcomes in diverse populations.