The routine blood test can only indicate the possible existence of viral infection, but cannot determine whether it is influenza virus infection.
The number of leukocytes and their classification in the routine blood count can indicate the presence of viral infection to a certain extent. Generally speaking, the ratio of neutrophils is 50~70% and the ratio of lymphocytes is 20~40%, and in the case of viral infection, the increase in the ratio of lymphocytes is often the main phenomenon, and it may be accompanied by a decrease in the total number of leukocytes.
However, blood counts cannot be used to confirm the diagnosis of influenza virus infection. The diagnosis of influenza virus infection can only be established if the symptoms of influenza are present and at least one of the following is present: a positive nucleic acid test for influenza virus, a positive test for influenza antigens, a positive culture culture isolation of influenza virus, and a 4-fold or greater increase in the level of influenza virus-specific IgG antibodies in both sera during the acute phase and during the recovery phase.
When influenza virus infection is suspected, it is recommended to seek prompt medical attention for standardized diagnosis and treatment if necessary.