Tracking COVID-19 Cases and Deaths in the United States: Distribution of Events by Day of Pandemic

In this paper, we analyze the progression of COVID-19 in the United States over a nearly one-year period beginning March 1, 2020, with a novel metric representing the partial-average day-of-event, where events are new cases and new deaths. The metric is calculated as a function of date and location to illustrate patterns of disease, showing growing or waning cases and deaths. The metrics enable the direct comparison of the time distribution of cases and deaths, revealing data coherence and how patterns varied over a one-year period. We also compare different methods of estimating actual infections and deaths to better understand on the timing and dynamics of the pandemic by state. We used three example states to graphically compare metrics as functions of date and also compared statistics derived from all 50 states. Over the period studied, average case day and average death day vary by two to five months among the 50 states, depending on data source, with the earliest averages in New York and surrounding states, as well as Louisiana. The average day of death has preceded the average day of case in Centers for Disease Control (CDC) data for most states and most dates since June of 2020. In contrast, “COVID-19 Projections” more closely align deaths and cases, which are similarly distributed.