Thymosin Alpha-1

The ten papers cited here were published between 1995 and 2025. Four are reviews: meta-analyses covering severe acute pancreatitis, acute exacerbations of COPD and moderate-to-critical COVID-19, and a systematic review of human clinical trials. Five are clinical studies. Four of those concern COVID-19 or its aftermath: a pilot trial in hospitalised patients with hypoxaemia and lymphocytopenia, an ex vivo study of lymphocytes from people with post-acute sequelae, a retrospective cohort and a multicentre cohort. The fifth is a 1995 multicentre trial in infertile men. The one preclinical paper examined tumour-associated macrophages in an oncolytic adenovirus model.

Several of these studies measured lymphocyte subsets. In the pilot trial, CD4+ T-cell counts rose faster than under standard care among patients who started on low-flow oxygen, and the pancreatitis meta-analysis reported higher CD4+ counts and CD4+/CD8+ ratios. In the ex vivo work, lymphocyte responses moved back towards an appropriate pattern, most clearly in samples from people who had been more severely ill during the acute phase. The systematic review described the peptide as well tolerated across the trials it covered. The 1995 trial reported an increase in the fertilising capacity of sperm, and the adenovirus study, in a preclinical tumour model, reported that the peptide reversed the macrophage polarisation the virus had induced.

The COVID-19 findings conflict. The 2022 retrospective cohort associated the peptide with lower 28-day mortality, while the 2021 multicentre cohort associated it with a higher rate of non-recovery, especially in more severe disease. Both were observational. The COVID-19 meta-analysis suggested a lower mortality rate but said randomised trials were still needed to verify it, and the COPD meta-analysis also called for more high-quality randomised trials. The only COVID-19 trial was a pilot, the post-acute findings are ex vivo, and the fertility and tumour results each rest on a single study, the fertility trial now three decades old. Read together, the studies agree more on T-cell counts than on clinical outcomes such as mortality.