Pediatric long COVID is characterized by myeloid CCR6 suppression and immune dysregulation

The biological mechanisms underlying long COVID in the pediatric population are poorly understood. Our study aimed to characterize the immune pathophysiology of long COVID in children and young people (CYP). We analyzed major immune cell compartments in PBMCs, as well as specific SARS-CoV-2 antibody response in CYP with (n=99) and without (n=18) long COVID at three months following acute infection. Our findings indicate that pediatric long COVID is associated with a dysregulated immune response characterized by altered innate immunity and overactivated T-, B- and NK-cell responses. Furthermore, CYP with long COVID had an impaired humoral response to SARS-CoV-2 marked by a dysregulated B-cell compartment and lower levels of anti-RBD IgG and IgA. This correlated with reduced neutralizing capacity against SARS-CoV-2. Random forest analysis identified CCR6 expression on myeloid cells as the most relevant biomarker that distinguishes long COVID from control individuals with 79% accuracy.