Inclusion Criteria:  Children over 0 days and under 16 years of age seen in consultation for the follow-up of their pathology or immunosuppressive treatment (see above, Groups of patients). Several cases groups will be considered in this study, presented with immunocompromised state or immunosuppressive treatment (i. e. children with: HIV infection, Hematologic Malignancy treated by conventional chemotherapy, Hematologic pathology treated by allogenic stem cell transplantation, inflammatory bowel disease treated by anti-TNF, idiopathic juvenile arthritis treated by methotrexate, treated by renal transplantation; see above, paragraph groups of patients for details).  Children over 0 days and under 16 years of age considered as control will be non-immunosuppressed children without chronic inflammation, attending consultation for preoperative assessment or congenital abnormalities of the kidney and urinary tract, for Nephropathies without renal impairment (eDFG > 45mL/min/1.73m), for non-inflammatory intestinal (polyposis, Chronic intestinal pseudo-obstruction, short bowel syndrome) or pancreatic (hereditary pancreatitis) pathologies.For comparisons, healthy children will be age-matched with each case.  Informed consent of the holder (s) of the exercise of parental authority Affiliation to a social security scheme  Exclusion Criteria:  Children who have a signs of a current infection. Use of immunoglobulins or blood products within 3 months prior to enrolment. Children who received one or more doses of SARS-Cov-2 vaccine.