Fig. 1

DNA methylation signature analysis of PBMC associated with PACS. a Multidimensional scaling (MDS) plot of the three groups; controls (Con, blue), COVID-19 convalescent group (CC19, orange) and patients with post-acute COVID-19 syndrome (PACS, red). Dimension 1 (x-axis) and dimension 2 (y-axis) show the distances between the samples using the top 1000 most variable CpG positions. Vaccinated (bold lines), non-vaccinated (fine lines). CC19s and Cons were collected during spring/summer of 2020. None of the CC19 or Cons was vaccinated (no vaccines available at that time). b Heatmap of differentially methylated CpGs (DMCs) representing an unsupervised hierarchical clustering analysis (Euclidean distance) of individual methylation (β values, hypomethylated; blue, hypermethylated, yellow, as indicated) of the 271 identified DMCs. The study groups are coloured as in panel a, and individual samples are arranged as columns. c Boxplots of β values (y-axis) showing the DNA methylation levels at three differentially methylated CpGs mapped to the SNORD3B, CETP, DLGAP1 genes, respectively, in each of the study group (x-axis)