Frequent quantitative changes	WBC↕ Neutrophils ↑ Lymphocytes ↓ Eosinophils may be↓ Basophils may be ↓ Monocytes may be ↓ Hemoglobin ↕ Platelets ↕
Frequent qualitative changes	• Atypical lymphocytes: ○ Plasmacytoida ○ Circulating plasma cellsa ○ Large granular lymphocytes (LGLs) ○ Cytoplasmic vacuoles •Myeloid left shift ± leukoerythroblastosisa •Smudged neutrophilsa •Neutrophil vacuolationa • Abnormal neutrophil segmentation: ○ Hyposegmentation or hypersegmentationa ○ Pseudo-Pelger–Huëta ○ Ring-shaped nucleia • Abnormal neutrophil granulation, cytoplasmic inclusions: ○ Varying toxic granulation ○ Hypogranularity ○ Blue-green inclusions ○ Howell-Jolly body-like inclusions ○ Döhle bodies •Large or giant plateletsa •Pyknotic cellsa •Eosinophils with multiple vacuoles •Monocyte vacuolization
Association with severe disease including death	•High WBC count • Increasing neutrophilia ○ Higher number of left-shifted/immature granulocytes ○ Ring-shaped neutrophils ○ Significant toxic granulation • Continuing decline in ALC ○ LGLs and reactive lymphocytes • Decline in absolute monocyte and eosinophil counts ○ Monocyte vacuolization •Low platelet count •Neutrophil to lymphocyte ratio (NLR) ↑ •Platelet to neutrophil ratio (PNR) ↑

^a Most significant morphologic findings in COVID-19 patients when compared with patients without COVID-19.