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. 2025 May 1;29(1):173.
doi: 10.1186/s13054-025-05395-7.

An urgent call to publish COVID-19 trials: a systematic search revealed ZERO studies regarding the incidence of thromboembolic events in SARS-CoV-2 Omicron-infected COVID-19 patients

Amon Faske  1 , Stefanie Reis  1 , Tamara Pscheidl  1 , Lena Saal-Bauernschubert  1 , Patrick Meybohm  1 , Stephanie Weibel  2
Affiliations

An urgent call to publish COVID-19 trials: a systematic search revealed ZERO studies regarding the incidence of thromboembolic events in SARS-CoV-2 Omicron-infected COVID-19 patients

Amon Faske et al. Crit Care. .

Abstract

Background: COVID-19 has been associated with an increased risk of thromboembolic complications, particularly in hospitalized patients. While early research focused on pre-Omicron variants, the thrombotic risk associated with SARS-CoV-2 Omicron infections remains unclear. Given the evolving nature of the pandemic, it is critical to assess whether current anticoagulation recommendations remain appropriate.

Methods: We conducted a systematic review of clinical studies to determine the incidence of thromboembolic events in COVID-19 patients infected with SARS-CoV-2 Omicron variants. The main outcome was thromboembolic events within 28 days of infection, using objective diagnostic criteria. We systematically searched the Cochrane COVID-19 Study Register, covering multiple databases, for studies published between November 30, 2021, and January 31, 2024. Studies were screened independently by two reviewers, and missing data were requested from study authors.

Results: Our search identified 7843 records, of which 238 underwent full-text screening. Ultimately, no study met our inclusion criteria due to issues such as lack of Omicron-specific data, inadequate reporting of diagnostic methods, and failure to specify the timing of outcome assessment. Despite contacting study authors, no additional eligible data were obtained.

Conclusion: There is currently no high-quality evidence on the incidence of thromboembolic events in Omicron-infected COVID-19 patients. The absence of relevant studies highlights a critical research gap and raises concerns about the applicability of current anticoagulation guidelines. Future studies should stratify outcomes by SARS-CoV-2 variant, ensure transparent reporting, and provide rigorous diagnostic confirmation to guide clinical decision-making.

Keywords: COVID-19; Omicron; SARS-CoV-2 variants; Systematic review; Thrombosis.

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Conflict of interest statement

Declarations. Ethics approval and consent to participate: Not applicable. Consent for publication: We, the authors, grant our consent for the publication of this work in its entirety. Competing interests: The authors declare no competing interests.

Figures

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Fig. 1
PRISMA flow diagram
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