Decrease in CD4 and CD8 lymphocytes are predictors of severe clinical picture and unfavorable outcome of the disease in patients with COVID-19.

Study objective: The main objective of this study was to investigate the association between CD4+ and CD8+ lymphocyte values and disease severity, need for oxygen therapy and disease outcomes. Design: The research was designed as a cross-sectional observational study. Setting: This study was conducted at the Clinic for Infectious Diseases, University Clinical Center Kragujevac, as a COVID-19 treatment center. Participants: The study group consisted of a total of 101 adult hospitalized patients with confirmed COVID-19 infection, excluding patients under 18 years of age, patients with malignant diseases, tuberculosis, hepatitis, immune disorders, pregnant women, or HIV-positive patients. SARS-CoV2 infection was diagnosed by rapid antigen tests or real-time reverse transcription polymerase chain reaction from a nasal swab. Interventions: The patients were classified into two groups based on oxygen therapy needs, disease severity, and disease outcomes. Results and conclusions: Low CD4+ and CD8+ T cell values were associated with severe clinical presentation, more need for oxygen therapy as well as poor disease outcome. Receiver operating characteristic analysis provided cutoff values to support predicting the aforementioned variables, establishing CD4+ and CD8+ values as significant prognostic biomarkers. Future studies should be aimed at identifying factors that lead to gender differences in the immune response.