Understanding the United States’ 50 most populous counties’ COVID-19 healthcare outcomes through multiple regression across the Delta variant and Omicron variant times of dominance

As new variants of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) continuously evolve and mutate, it is vital to understand how novel and emerging variants affect public health outcomes. Our understanding of COVID-19 can have significant impacts on how we approach measures to mitigate the virus’s deleterious effects on the world. Therefore, in this study, we aim to 1) quantify the relationships between county-characteristics, such as the proportion of residents vaccinated, and certain county-level health outcomes related to COVID-19 such as: case counts, death counts, positivity rates, infection rates, ICU occupancy levels, hospitalizations, and the proportion of ICU admissions due to COVID-19. We also aim to 2) compare these relationships across three different time periods - two periods where Delta was the dominant strain of the U.S. and one period where Omicron was the dominant strain of the U.S. In this study, we used multiple regression to measure the strength of relationships between healthcare outcomes and county characteristics from June 20, 2021 to March 19, 2022, which span across three time periods. The first two time periods, June 20, 2021 to September 18, 2021 and September 19, 2021 to December 18, 2021, are when Delta was dominant (> 50% of cases) in the U.S. and the third period, December 19, 2021 to March 19, 2022, is during Omicron’s dominance (up to March 19, 2022).