A meta‑analysis of eight studies suggests that adding thymosin‑alpha‑1 to standard care for moderate to critical COVID‑19 patients may cut the death rate by about 40%, but it doesn’t seem to change how long people stay in the hospital or whether they need a ventilator. The benefit appears stronger in larger studies and may differ between men and women. More high‑quality trials are still needed.

Effort to search for the optimal COVID-19 treatment has continuously been attempted. Thymosin alpha-1 have immunomodulatory properties which may be beneficial in case of viral infection. This study's goal is to determine whether thymosin alpha-1 is effective in treating people with moderate-to-severe COVID-19. We searched for literature in 4 database: Scopus, Europe PMC, Medline, ClinicalTrials.gov, and Cochrane Library until March 25th, 2023. If those articles have data on the efficacy of thymosin alpha-1 therapy on COVID-19, they would be included. Risk ratio (RR) and Mean Difference (MD) along with their 95% confidence intervals were used to pool the results of dichotomous and continuous variables, respectively. Pooled data from 8 studies indicated that moderate to critical Covid-19 patients who were receiving thymosin alpha-1 therapy had significantly lower mortality from COVID-19 (RR 0.59; 95% CI 0.37-0.93, p = 0.02, I² = 84%), but without any difference in the needs for mechanical ventilation (RR 0.83; 95% CI 0.48-1.44, p = 0.51, I² = 74%) and hospital length of stay (MD 2.32; 95% CI - 0.93, 5.58, p = 0.16, I² = 94%) compared to placebo. The benefits of thymosin alpha-1 on the mortality rate were significantly affected only by sample size (p = 0.0000) and sex (p = 0.0117). Our study suggests that treatment with thymosin alpha-1 may reduce mortality rate in moderate to critical COVID-19 patients. Randomized clinical trials (RCTs) are still required to verify the findings of our study.