COVID-19 in children and young adults with moderate/severe inborn errors of immunity in a high burden area in pre-vaccine era.

BACKGROUND: Information regarding inborn error of immunity (IEI) as a risk factor for severe COVID-19 is scarce. We aimed to determine if paediatric patients with moderate/severe IEI got COVID-19 at the same level as the general population, and to describe COVID-19 expression. MATERIAL AND METHODS: We included patients with moderate/severe IEI aged 0-21 years old: cross-sectional study (June2020) to determine the prevalence of COVID-19; prospective study (January2020-January2021) including IEI patients with COVID-19. Assays used: nasopharyngeal swab SARS-CoV-2 PCR and SARS-CoV-2-specific immunoglobulins. RESULTS: Seven from sixty-five patients tested positive (prevalence: 10.7% (7%-13%)) after the first SARS-COV-2 wave and 13/15 patients diagnosed with COVID-19 had an asymptomatic/mild course. CONCLUSIONS: In our area, prevalence of COVID-19 in moderate/severe IEI paediatric patients after the first wave was slightly higher than in the general population. The majority of patients presented a benign course, suggesting a possible protective factor related with age despite IEI.

Kinetics of humoral deficiency in CART19-treated children and young adults with acute lymphoblastic leukaemia.

CD19-CAR T-cell therapy (CART19) causes B-cell aplasia (BCA) and dysgammaglobulinemia but there is a lack of information about the degree of its secondary immunodeficiency. We conducted a prospective study in children and young adults with acute lymphoblastic leukaemia treated with CART19, analysing the kinetics of BCA and dysgammaglobulinemia during therapy, as well as the B-cell reconstitution in those with CART19 loss. Thirty-four patients were included (14 female) with a median age at CART19 infusion of 8.7 years (2.9-24.9). Median follow-up after infusion was 7.1 months (0.5-42). BCA was observed 7 days after infusion (3-8), with persistence at 24 months in 60% of patients. All patients developed a progressive decrease in IgM and IgA: 71% had undetectable IgM levels at 71 days (41-99) and 13% undetectable IgA levels at 185 days (11-308). Three of 12 patients had protective levels of IgA in saliva. In two of three patients who lost CART19, persistent B-cell dysfunction was observed. No severe infections occurred. In conclusion, BCA occurs soon after CART19 infusion, with a progressive decrease in IgM and IgA, and with less impairment of IgA, suggesting the possibility of an immune reservoir. A persistent B-cell dysfunction might persist after CART19 loss in this population.