Outcomes of SARS-CoV-2 Omicron Variant Infections Compared with Seasonal Influenza and Respiratory Syncytial Virus Infections in Adults Attending the Emergency Department: A Multicentre Cohort Study.
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Hedberg P, Karlsson Valik J, Abdel Halim L, Alfvén T, Naucler P
Clin Infect Dis - (-) - [2023-10-26; online 2023-10-26]
There is a controversy over the impact of SARS-CoV-2 infections in an era of less virulent variants and an increasing population immunity. We compared outcomes in adults attending the emergency department (ED) with an Omicron, influenza, or respiratory syncytial virus (RSV) infection. Retrospective multicentre cohort study including adults attending the ED in six acute care hospitals in Stockholm County, Sweden, with an Omicron, influenza, or RSV infection during 2021-22 and 2015-19. During 2021-22, patients were tested for all three viruses by multiplex PCR testing. The primary outcome was 30-day all-cause mortality. Secondary outcomes were 90-day all-cause mortality, hospitalization, and intensive care unit (ICU) admission. A total of 6,385 patients from 2021-22 were included in the main analyses: 4,833 Omicron, 1,099 influenza, and 453 RSV. The 30-day mortality was 7.9% (n=381) in the Omicron, 2.5% (n=28) in the influenza, and 6.0% (n=27) in the RSV cohort. Patients with Omicron had an adjusted 30-day mortality odds ratio (OR) of 2.36 (95% confidence interval [CI] 1.60-3.62) compared with influenza and 1.42 (95% CI 0.94-2.21) compared with RSV. Among unvaccinated Omicron patients, stronger associations were observed compared with both influenza (OR 5.51 [95% CI 3.41-9.18]) and RSV (OR 3.29 [95% CI 2.01-5.56]). Similar trends were observed for secondary outcomes. Findings were consistent in comparisons with 5,709 pre-pandemic influenza 995 RSV patients. In patients attending the ED, infections with Omicron were both more common and associated with more severe outcomes compared with influenza and RSV, in particular among unvaccinated patients.
PubMed 37883521
DOI 10.1093/cid/ciad660
Crossref 10.1093/cid/ciad660
pii: 7330559