HFC-IgG-seq/HFG-IgA-seq will be conducted on serum and stool samples from patients following the methods outlined by Vujkovic-Cvijin et al2655 with slight modifications: (1) the patient’s serum (IgG-seq+IgA seq) and stool (IgA-seq) samples will be used directly against their faecal sample (faecal microbiome) for immune response to commensal microbes; (2) shotgun sequencing will be used instead of 16S rRNA amplicon sequencing expanding the potential to identify other microbial commensals (eg, fungal, protozoan, etc.)that the host raises an immune response to during PASC-IBS. This evidence concerns the gene CD79A and long COVID-19.