Analyzing COVID-19 Deaths by Weekday: A Four-Year Statistical Review (2020–2023)

Background. Earlier studies have suggested that the mortality rate of Coronavirus Disease-2019 (COVID-19) may vary by day of the week, possibly due to variations in healthcare system workflows or reporting delays. This study aimed to assess whether such day-of-week effects exist in COVID-19 death data from 2020 to 2023 in the United States. Materials and Methods. We extracted nationwide United States COVID-19 mortality data from the Centers for Disease Control and Prevention WONDER database, grouping deaths by weekday for each year from 2020 to 2023. Negative binomial regression and Tukey’s Honest Significant Difference test were used to assess differences in daily death counts. Additional comparisons were made between aggregated weekday (Monday–Friday) and weekend (Saturday–Sunday) totals. Results. No statistically significant differences were observed in the number of deaths across individual weekdays in any year analyzed (p = 0.905 for all years combined). Post-hoc testing confirmed that all pairwise comparisons between weekdays were non-significant. Sub-analyses of early (2020–2021) and late (2022–2023) pandemic periods also showed no significant variation (all p-values >0.05). The average number of deaths was slightly higher on weekdays throughout the study period in the weekday-versus-weekend analysis; however, the combined difference did not reach statistical significance (p = 0.947). Conclusion. Official COVID-19 mortality data from 2020 to 2023 in the United States show no evidence of a “weekend effect,” indicating that the day of the week did not significantly influence reported deaths.