Supporting these findings, studies looking at immune dysregulation in subjects with LC who had mild acute COVID-19 have found T-cell alterations [38], including exhausted T-cells, reduced CD4+ and CD8+ effector memory cell numbers [39], and elevated PD-1 expression on central memory cells, persisting for at least 13 months. This evidence concerns the gene CD4 and laryngotracheoesophageal cleft.