There is a significant difference between bacterial and viral infections in the blood picture. Bacterial infections tend to have a significantly elevated total white blood cell count and leukocyte classification, often >10,000/ml, with neutrophils above 70%. million/ml or less, while the classification is dominated by elevated lymphocytes. Therefore, there is a very big difference between viral and bacterial infections clinically. Of course, sometimes the patient is immunocompromised and the leukocyte response is not obvious, or the leukocyte may be within the normal range, and then other related tests, such as blood culture, are needed to clarify. If the blood culture has positive bacteria, it means bacterial infection, while if the antibodies to the virus are elevated, it is more likely to be a viral infection.