Clinical Outcomes of Hospitalized Patients with SARS-CoV-2 Omicron Variant vs. Influenza A During Influenza Season 2021 to 2022: A Retrospective Observational Study

Alaa Atamna*, Evgeny Berkov, Genady Drozdinsky, Tzippy Shochat, Haim Ben Zvi, Noa Eliakim-Raz, Jihad Bishara, Avishay Elis

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Background: Influenza and coronavirus disease 2019 (COVID-19) are respiratory diseases with similar modes of transmission. In December 2021, influenza re-emerged after it had been undetected since March 2020 and the Omicron variant replaced the Delta variant. Data directly comparing the two diseases are scarce. Objectives: To compare the outcomes of patients with both the Omicron variant and influenza during 2021-2022. Methods: We performed a retrospective study conducted in Beilinson hospital, Israel, from December 2021 to January 2022. We included all hospitalized patients with either laboratory-confirmed COVID-19 or influenza. The primary outcome was 30-day mortality. Results: We identified 167 patients diagnosed with Omicron and 221 diagnosed with Influenza A. The median age was 71 years for Omicron and 65 years for influenza. Patients with Omicron had a significantly higher Charlson Comorbidity Index score (4 vs. 3, P < 0.001). Patients with Omicron developed more respiratory failure that needed mechanical ventilation (7% vs. 2%, P= 0.05) and vasopressors (14% vs. 2%, P< 0.001) than patients with influenza. In a multivariate model, 30-day mortality was lower in patients diagnosed with influenza than in patients diagnosed with Omicron (19/221 [9%] vs. 44/167 [26%], hazard ratio 0.45,95% confidence interval 0.25-0.81). Conclusions: Patients diagnosed with Omicron had higher mortality than patients diagnosed with seasonal influenza. This finding could be due to differences in co-morbidities, the virus pathogenicity, and host responses to infection.

Original languageEnglish
Pages (from-to)585-589
Number of pages5
JournalIsrael Medical Association Journal
Volume25
Issue number9
StatePublished - Sep 2023

Keywords

  • Omicron vaiant
  • coronavirus disease 2019 (COVID-19)
  • influenza
  • mortality
  • outcomes

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