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

Background: Earlier studies suggested that coronavirus disease 2019 (COVID-19) mortality may vary by the day of the week, possibly due to healthcare system workflows or reporting delays. This study aimed to assess whether such day-of-week effects exist in U.S. COVID-19 death data from 2020 to 2023. Methods: We extracted nationwide US COVID-19 mortality data from the CDC WONDER database, grouping deaths by weekday for each year from 2020 to 2023. A one-way ANOVA (Analysis of Variance) and Tukey’s HSD (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= 1.000 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). In the weekday-versus-weekend analysis, average deaths were slightly higher on weekdays during 2020–2021 and marginally higher on weekends during 2022–2023, but none the combined difference failed to reach statistical significance (p=0.969). Conclusions: Official COVID-19 mortality data from 2020 to 2023 in the US show no evidence of a “weekend effect,” indicating that day of the week did not significantly influence reported deaths.