Hematological and Morphological Changes in the Peripheral Blood Smear of Patients with COVID-19

Background: The novel coronavirus is responsible for a widespread pandemic, causing multiple clinical manifestations. Peripheral blood films have shown changes in white blood cell (WBC) morphology and counts, as well as platelet abnormalities. Atypical and reactive lymphocytes may also be observed in the blood film, which suggests mild leukoerythroblastosis. Objectives: The present study aimed to evaluate the hematological and morphological changes in the peripheral blood smear of patients with COVID-19. Methods: This study was conducted on 175 patients diagnosed with COVID‐19 infection. Blood samples were collected from the patients and examined for the estimation of blood parameters, differential cell count, and presence of atypical lymphocytes. Results: The mean age of the patients was 53.73 years, and males constituted 52.6% of the patients. The majority had normal hemoglobin levels. WBC count was normal in 60.6% of the patients, while 74.3% had normal platelet count, and thrombocytopenia was detected in 23.4%. In addition, differential WBC count indicated that 56.6% of the patients had normal neutrophils, while lymphopenia was detected in 28 and 77.7% had a low eosinophil count. The peripheral blood smears showed atypical lymphocytes with deeply basophilic cytoplasm in 21.14% of the patients. Conclusions: Blood film examination may show multiple abnormal findings in patients with COVID-19 infection. Neutrophilia and lymphopenia with the presence of atypical lymphocytes are frequently observed as well. Low eosinophil count is also highly common. Although platelets showed changes, they were normal or reduced in most cases.