We have observed increased percentages of regulatory T cells (Tregs) within the CD4+ population in IPF patients when compared to healthy controls (10.51% vs 7.78%; p=0.002 before vaccination; 14.46% vs 9.23%; p=0.006 after the 1st dose; 16.40% vs 8.65%; p<0.000 after the 2nd dose of vaccine) (Figure 2A) (PCA 1-3; Supplementary Table 4; Supplementary Data). This evidence concerns the gene CD4 and idiopathic pulmonary fibrosis.