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 this population. We analyzed major immune cell compartments in PBMCs and the specific SARS-CoV-2 antibody response in 99 patients with long COVID and in 18 patients without long COVID at 3 months after 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, young people 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 individuals with long COVID from control individuals with 79% accuracy.