Lymphocyte subsets early predict mortality in a large series of hospitalized COVID‐19 patients in Spain

Disbalanced lymphocyte subpopulations are early markers of mortality in our series of 701 SARS‐CoV‐2 infected patients, when severe lymphopenia has yet to develop. If available, the study of lymphocyte subsets by flow cytometry is recommended to identify high‐risk COVID‐19 patients at hospital admission. Summary The role of lymphocytes and their main subsets as prognostic factors of death in SARS‐CoV‐2‐infected patients remains unclear, with no information obtained from patients outside China. We aimed to assess whether measuring lymphocyte subpopulations added clinical value to the total lymphocyte counting regarding mortality when they were simultaneously tested at hospital admission. Peripheral blood was analysed in 701 polymerase chain reaction (PCR)‐confirmed consecutive patients by lysed–no washed flow cytometry. Demographic and clinical features were registered in electronic medical records. Statistical analysis was performed after a 3‐month follow‐up. The 112 patients who died were older and had significantly higher frequencies of known co‐morbidities than survivor COVID‐19 patients. A significant reduction in total lymphocytes, CD3+, CD4+, CD8+ and CD19+ counts and CD3+ percentage was found in the group of deceased patients (P