Effect of thymalfasin (Thymosin-α-1) on reversing lymphocytopenia among patients with COVID-19

Introduction: Thymosin-α-1 (Tα1) elevates lymphocyte counts among patients with COVID-19, but its effect on reversing lymphocytopenia is unknown. Methods: 24 patients treated with Tα1 and 100 patients in the control arm were included in this analysis. The incidence rate of reversing lymphocytopenia, overall and stratified by baseline oxygen support, above the threshold for classification of lymphocytopenia (i.e., Total Lymphocyte Count (TLC) < 1.5 × 10⁹/L) and severe lymphocytopenia (i.e., TLC < 1.0 × 10⁹/L) within 3, 5, and 7 days of treatment initiation was calculated, along with incidence rate ratios (IRRs) and 95 % confidence intervals (CIs). Results: Compared with the standard of care, the rate of reversing lymphocytopenia (IRR: 2.38, 95 % CI: 0.92 – 5.81) and severe lymphocytopenia (IRR: 1.57, 95 % CI: 0.60 – 3.72), especially among patients with severe lymphocytopenia on high flow oxygen support (IRR: 3.64, 95 % CI: 0.71 – 23.44), was greater for patients treated with Tα1 within 3 days of treatment initiation, although analyses were not significant. Conclusion: Among patients with hypoxemia and lymphocytopenia, Tα1 may reverse lymphocytopenia and severe lymphocytopenia, particularly within 3 days of treatment initiation, faster than the standard of care.