Immature Platelets and Disease Severity in Patients Hospitalized with Acute COVID-19 Who Are Vaccinated Against COVID-19

Introduction: COVID-19 has killed more than four million people worldwide and resulted in strained health resources globally(Dong Lancet ID 2020). There is a critical need for prognostic biomarkers to predict severity and outcomes in COVID-19 patients to allow more efficient resource allocation. Studies using pre-vaccination hospitalized patient data have demonstrated that elevated initial and peak immature platelet fraction (IPF), as well as related platelet indices, were associated with progression to severe COVID-19 outcomes (Welder Br J Haem 2021). This suggests the potential role of immature platelets as a cost-effective biomarker. The underlying pathophysiology of immature platelets in COVID-19 is unclear but these results support the hypothesis of higher inflammatory response, leading to thrombopoiesis mediated by pro-inflammatory cytokines and platelet hyper-reactivity in this population (Manne Blood 2021). It is unclear if this holds true in patients vaccinated against COVID-19. This study aims to assess the relationship between immature platelets in patients vaccinated against COVID-19 and hospitalized with acute COVID-19.