Prevalence of Pneumonia Among Patients Who Died with COVID-19 Infection in Ancestral Versus Omicron Variant Eras

Rationale and Objectives: The Omicron variant of COVID-19 is less severe than the ancestral strain, leading to the potential for deaths in patients infected with the virus but who die of other causes. This study evaluated the difference in rates of pneumonia among patients who died with SARS-CoV-2 infection in the ancestral vs Omicron eras. Materials and Methods: We identified patients who died within 30 days of a positive SARS-CoV-2 test, from March 2020 through December 2022; variants were assigned based on the prevalent variant in the US at that time. We also obtained a control group from patients who died within 30 days of a negative SARS-CoV-2 test in January 2022. The first CT after the test was reviewed in a blinded fashion and assigned a category from the RSNA Consensus Reporting Guidelines. The primary outcome was the difference in rates of positive (typical or indeterminate) COVID-19 findings in the ancestral vs Omicron eras. Results: A total of 598 patients died during the ancestral era and 400 during the Omicron era, and 347 decedents comprised the control group. The rate of positive COVID-19 findings was 67/81 (83%) in the ancestral era and 43/81 (53%) in the Omicron era (P < .001), an absolute difference of 30% (95% CI 16%-43%). The rate of positive findings in the control group was 23/76 (30%). Conclusion: During the Omicron era, 30% fewer SARS-CoV-2-associated deaths were associated with COVID-19 pneumonia and were caused either by nonpulmonary effects of the infection or were unrelated to the infection.