Burden Beyond COVID-19: A Retrospective Statistical Analysis of Overlapping Mortality Patterns of COVID-19, Pneumonia, and Influenza in the United States (2020–2023)

The COVID-19 pandemic caused unprecedented mortality worldwide. However, the contribution of other respiratory illnesses such as pneumonia and influenza to COVID-19 mortality patterns remains underexplored. This retrospective study utilized provisional mortality data from the Centers for Disease Control and Prevention (CDC) spanning January 2020 to September 2023. Descriptive statistics characterized mortality trends for COVID-19, pneumonia, and influenza, and Pearson correlation analyses assessed the relationships between these causes of death. A multiple linear regression model evaluated the predictive value of pneumonia and influenza deaths on COVID-19 deaths. COVID-19 deaths demonstrated a strong positive correlation with pneumonia deaths (r = 0.994, p < 0.001) and influenza deaths (r = 0.893, p < 0.001). Pneumonia deaths and influenza deaths were also strongly correlated (r = 0.916, p < 0.001). The regression model revealed that pneumonia and influenza deaths together explained 99.1% of the variance in COVID-19 deaths (R² = 0.991, p < 0.001), with an F-statistic of 3,413,611.848 (p < 0.001). Seasonal trends showed mortality peaks during winter months across all pandemic years. These findings highlight the significant overlap among COVID-19, pneumonia, and influenza mortality and emphasize the need for integrated respiratory disease surveillance and intervention programs.