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Platelet aggregates, a marker of severe COVID-19 disease
  1. Alexandros Rampotas,
  2. Sue Pavord
  1. Haematology Department, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
  1. Correspondence to Dr Alexandros Rampotas, Haematology Department, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK; alexandros.rampotas{at}


Thrombocytopenia is common in an intensive care unit (ICU) setting due to endogenous and iatrogenic factors. Despite that, thrombocytopenia in patients with severe COVID-19 infections is surprisingly uncommon. By examining the blood film of 20 ICU patients with COVID-19, we observed the presence of platelet aggregates and macrothrombocytes indicating increased platelet activity. We compared these findings with 20 blood films of non-severe COVID-19 cases where these findings were absent. These morphology features could be consistent with severe COVID-19 infection and is further evidence of the important role that platelets play when COVID-19 manifests with thrombotic complications or respiratory failure.

  • blood platelets
  • thrombosis
  • morphological and microscopic findings

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  • Handling editor Mary Frances McMullin.

  • Twitter @ARampotas

  • Contributors AR and SP conceived the idea, collected the data, drafted and critically evaluated the manuscript, and approved the final version of this manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.