Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Multicenter Study
. 2023 Feb 1;6(2):e2255599.
doi: 10.1001/jamanetworkopen.2022.55599.

Hospital Outcomes of Community-Acquired SARS-CoV-2 Omicron Variant Infection Compared With Influenza Infection in Switzerland

Lea Portmann  1 , Marlieke E A de Kraker  2 , Georg Fröhlich  3   4 , Amaury Thiabaud  5 , Maroussia Roelens  5 , Peter W Schreiber  6 , Nicolas Troillet  7   8 , Anne Iten  2 , Andreas Widmer  8   9 , Stephan Harbarth  2   8 , Rami Sommerstein  1   8   10 ; CH-SUR study group
Collaborators, Affiliations
Multicenter Study

Hospital Outcomes of Community-Acquired SARS-CoV-2 Omicron Variant Infection Compared With Influenza Infection in Switzerland

Lea Portmann et al. JAMA Netw Open. .

Abstract

Importance: With the ongoing COVID-19 pandemic, it is crucial to assess the current burden of disease of community-acquired SARS-CoV-2 Omicron variant in hospitalized patients to tailor appropriate public health policies. Comparisons with better-known seasonal influenza infections may facilitate such decisions.

Objective: To compare the in-hospital outcomes of patients hospitalized with the SARS-CoV-2 Omicron variant with patients with influenza.

Design, setting, and participants: This cohort study was based on a national COVID-19 and influenza registry. Hospitalized patients aged 18 years and older with community-acquired SARS-CoV-2 Omicron variant infection who were admitted between January 15 and March 15, 2022 (when B.1.1.529 Omicron predominance was >95%), and hospitalized patients with influenza A or B infection from January 1, 2018, to March 15, 2022, where included. Patients without a study outcome by August 30, 2022, were censored. The study was conducted at 15 hospitals in Switzerland.

Exposures: Community-acquired SARS-CoV-2 Omicron variant vs community-acquired seasonal influenza A or B.

Main outcomes and measures: Primary and secondary outcomes were defined as in-hospital mortality and admission to the intensive care unit (ICU) for patients with the SARS-CoV-2 Omicron variant or influenza. Cox regression (cause-specific and Fine-Gray subdistribution hazard models) was used to account for time-dependency and competing events, with inverse probability weighting to adjust for confounders with right-censoring at day 30.

Results: Of 5212 patients included from 15 hospitals, 3066 (58.8%) had SARS-CoV-2 Omicron variant infection in 14 centers and 2146 patients (41.2%) had influenza A or B in 14 centers. Of patients with the SARS-CoV-2 Omicron variant, 1485 (48.4%) were female, while 1113 patients with influenza (51.9%) were female (P = .02). Patients with the SARS-CoV-2 Omicron variant were younger (median [IQR] age, 71 [53-82] years) than those with influenza (median [IQR] age, 74 [59-83] years; P < .001). Overall, 214 patients with the SARS-CoV-2 Omicron variant (7.0%) died during hospitalization vs 95 patients with influenza (4.4%; P < .001). The final adjusted subdistribution hazard ratio (sdHR) for in-hospital death for SARS-CoV-2 Omicron variant vs influenza was 1.54 (95% CI, 1.18-2.01; P = .002). Overall, 250 patients with the SARS-CoV-2 Omicron variant (8.6%) vs 169 patients with influenza (8.3%) were admitted to the ICU (P = .79). After adjustment, the SARS-CoV-2 Omicron variant was not significantly associated with increased ICU admission vs influenza (sdHR, 1.08; 95% CI, 0.88-1.32; P = .50).

Conclusions and relevance: The data from this prospective, multicenter cohort study suggest a significantly increased risk of in-hospital mortality for patients with the SARS-CoV-2 Omicron variant vs those with influenza, while ICU admission rates were similar.

PubMed Disclaimer

Conflict of interest statement

Conflict of Interest Disclosures: Dr de Kraker reported receiving grants from Innovative Medicines Initiative Joint Undertaking outside the submitted work. Dr Thiabaud reported receiving grants from the Federal Office of Public Health during the conduct of the study. Dr Schreiber reported receiving grants from the Federal Office of Public Health during the conduct of the study and receiving grants from Pfizer and Gilead to attend PWS; receiving grants from the Medical Faculty of the University of Zürich; receiving personal fees from Pfizer; and serving on the advisory boards of Pfizer and Gilead outside of submitted work. Dr Iten reported receiving support for data collection form the Federal Office of Public Health during the conduct of the study. Dr Harbarth reported receiving grants from the Federal Office of Public Health during the conduct of the study and receiving grants from European Commission outside the submitted work. No other disclosures were reported.

Figures

Figure 1.
Figure 1.. Study Flowchart
Figure 2.
Figure 2.. Cumulative Incidence Plot for Mortality
Mortality with discharge as competing risk, by disease status (the SARS-CoV-2 Omicron variant vs influenza).
Figure 3.
Figure 3.. Cumulative Incidence Plot for Intensive Care Unit (ICU) Admission
ICU admission with discharge and death before ICU admission as competing risk, by disease status (the SARS-CoV-2 Omicron variant vs influenza).
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Nyberg T, Ferguson NM, Nash SG, et al. ; COVID-19 Genomics UK (COG-UK) consortium . Comparative analysis of the risks of hospitalisation and death associated with SARS-CoV-2 Omicron (B.1.1.529) and Delta (B.1.617.2) variants in England: a cohort study. Lancet. 2022;399(10332):1303-1312. doi:10.1016/S0140-6736(22)00462-7 - DOI - PMC - PubMed
    1. Bundesamt für Gesundheit . COVID-19 Schweiz. Updated March 20, 2022. Accessed March 20, 2022. https://www.covid19.admin.ch/de/epidemiologic/virus-variants
    1. World Health Organization . Classification of Omicron (B.1.1.529): SARS-CoV-2 variant of concern. Accessed July 20, 2022. https://www.who.int/news/item/26-11-2021-classification-of-omicron-(b.1....
    1. Lewnard JA, Hong VX, Patel MM, Kahn R, Lipsitch M, Tartof SY. Clinical outcomes among patients infected with Omicron (B.1.1.529) SARS-CoV-2 variant and BA.1/BA.1.1 or BA.2 subvariant infection in southern California. Nat Med. 2022;28(9):1933-1943. doi:10.1038/s41591-022-01887-z - DOI - PMC - PubMed
    1. Veneti L, Bøås H, Bråthen Kristoffersen A, et al. . Reduced risk of hospitalisation among reported COVID-19 cases infected with the SARS-CoV-2 Omicron BA.1 variant compared with the Delta variant, Norway, December 2021 to January 2022. Euro Surveill. 2022;27(4):2200077. doi:10.2807/1560-7917.ES.2022.27.4.2200077 - DOI - PMC - PubMed

Publication types

Supplementary concepts