SARS-CoV-2 and influenza are primary causes of viral community-acquired pneumonia (CAP). Both pathogens have exhibited high transmissibility and are recognized causes of pandemics. Controversy still exists regarding the clinical outcomes between patients hospitalized with CAP due to these viruses. This secondary analysis identified patients with either influenza or SARS-CoV-2 infections from three cohorts of patients hospitalized for CAP. Clinical outcomes between patients with CAP due to influenza or due to SARS-CoV-2 were evaluated. Primary outcomes included length of stay and in-hospital mortality. To account for population differences between cohorts, each case of influenza CAP was matched to two controls with SARS-CoV-2 CAP. Matching criteria included sex, age, and nursing home residency. Stratified cox-proportional hazards regression or conditional logistic regression were used where appropriate. A total of 259 patients with influenza CAP were matched to two controls with SARS-CoV-2 CAP, totaling to 518 controls. Patients with SARS-CoV-2 CAP were 2.23 times more likely to remain hospitalized at any point in time (95% confidence interval: 1.77-2.80), and had 3.84 times higher odds of dying in-hospital (95% confidence interval: 1.91-7.76) when compared to patients with influenza CAP. After matching and adjusting for confounding variables, patients admitted with SARS-CoV-2 CAP had consistently worse outcomes in comparison to their influenza CAP counterparts. This information can help clinicians decide on the level of care needed for patients with confirmed infections due to these pathogens. Additionally, estimates of disease burden can inform individuals at-risk for poor clinical outcomes, and further highlight the importance of effective preventative strategies.
Keywords: COVID-19; influenza; invasive mechanical ventilation; nursing home; pandemic.