The 2019 novel coronavirus (2019-nCoV) or the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has emerged as a pandemic threat from December 2019. Coronavirus can cause varying degrees of illness that range from mild to severe or fatal disease. The exact mechanism on hematopoiesis induced by this coronavirus is not yet well understood, but scientific evidence indicates that COVID-19 can cause hematological changes in infected patients. The present study summarized pieces of

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... re regarding hematologic findings of COVID-19 and their correlation with disease severity. Finally, we offered some laboratory abnormalities which help to differentiate severe COVID-19 from non-severe forms of the disease. Among hematological parameters, decreased hemoglobin rather than anemia, leukocytosis, lymphopenia, neutrophilia, and thrombocytopenia have been observed in conducted studies in some patients with COVID19. Furthermore, as the disease progresses to severe COVID-19, hemoglobin decline, leukocytosis, lymphopenia, neutrophilia, and thrombocytopenia continue to exacerbate. In addition, the neutrophil-tolymphocyte ratio is also considered as an independent risk factor for severe infection in COVID-19 patients.