Influenza A is a common respiratory infectious disease, and its clinical manifestations and prognosis are influenced by multiple factors. To analyze the characteristics of peripheral blood leukocyte and lymphocyte counts in patients with influenza A, and to explore their clinical significance in the assessment of influenza A severity. Early symptoms of influenza A lack specificity and are easily confused with other respiratory infections; as a simple, rapid, and basic laboratory test, the complete blood count can provide clues for early identification.

We retrospectively analyzed 159 patients with influenza A who were admitted to our hospital between January 2023 and February 2025, categorizing them into a non-severe group (mild and moderate) and a critical group (severe and critical). We compared the gender, age, duration of illness, and leukocyte and lymphocyte counts at admission and discharge between the two groups to investigate their clinical characteristics.

In the observation group, there were 39 males (81.25%), and in the control group, there were 71 males (63.96%); males accounted for the majority in both groups. The time to onset (4.33±4.18) d, length of hospital stay (17.21±9.91) d, and total disease duration (21.54±11.16) d in the observation group were compared with those in the control group (1.88±1.81) d, (10.23±4.11) d, and (12.11±4.68) d, and the differences were statistically significant (P<0.05). The white blood cell count in the observation group was 7.56(4.78, 11.30)×10⁹/L at admission and 7.32(5.82, 9.48)×10⁹/L at discharge, which were significantly higher than those in the non critical group [5.64(4.20, 7.48)×10⁹/L at admission and 5.46(4.34, 7.57)×10⁹/L at discharge] (P<0.005); The lymphocyte count in the observation group was 0.50(0.29, 0.75)×10⁹/L at admission and 0.86 (0.60, 1.46)×10⁹/L at discharge, which were significantly lower than those in the non critical group [0.92(0.63, 1.40)×10⁹/L at admission and 1.34(1.01, 1.73)×10⁹/L at discharge] (P<0.005). ROC curve analysis indicated that the leukocyte and lymphocyte counts at discharge were good predictors of patient survival. Further COX regression analysis showed that the lymphocyte levels at discharge significantly affected the risk of death in patients, while the impact of leukocyte count was less significant. Kaplan-Meier survival analysis indicated that leukocyte and lymphocyte counts within the normal range were associated with better prognosis.

The leukocyte and lymphocyte counts in patients with influenza A are important for clinical classification and prognosis, which means these indicators should be taken seriously in clinical management to improve patient prognosis and survival rates. Future research could look into the clinical value and potential mechanisms of these indicators.