PTMA and COVID-19: One indication that thymic function participates in COVID-19 disease severity has been reported, in which thymosin alpha-1 (T α 1, a synthetic thymic peptide) reduced the mortality of patients with severe COVID-19 [21], and a clinical trial with T α 1 to treat COVID-19 infection in elderly patients was approved (https://clinicaltrials.gov/ct2/show/NCT04428008 (12 January 2021)).