HUMORAL AND CELLULAR RESPONSE TO THE COVID-19 VACCINE IN IMMUNOCOMPROMISED CHILDREN

RUSSO C; SEERY V; URANGA, M; RAIDEN S; ALGIERI, S; DE CARLI N; BORDA, MAURICIO; OTERO, ADRIÁN; SANANEZ I; ALBISTUR MF; HEINITZ L; MARCO DEL PONT M; PARDINI M; BUDANO G; ALVAREZ L; SIMAZ N; MEHRAR C; QUINTANA MC; GARBINI C; AEDO PORTELA L; PEREYRA M; FERRERO FERNANDO; GEFFNER J; ARRUVITO L

Congreso; Reunión Anual de SAI 2023; 2023

Background: Developing an optimal vaccine-induced anti-SARS-CoV-2 protective immunity depends on a fully competent immune system. Some evidence was gathered on the effects of vaccination outcomes in immunocompromised adults. But few observations have been made regarding immunocompromised children in terms of strength and perdurability. We aimed to determine the humoral and cellular immune response to the 2nd and 3rd COVID-19 vaccine in immunocompromised children.Methods: Two cohorts were included (healthy and immunocompromised children), aged between 5-17 years, who received two (n=50) or three doses (n=22) of a first series COVID-19 vaccine (BBIBP-CorV and/or mRNA vaccines). The median time since the 2nd dose until sampling was 462 days and since the 3rd dose was 300 days. Plasma levels of anti-spike IgG antibodies, neutralizing activity, and antigen-specific T cells against the ancestral variant (Wuhan) and the variant of concern Omicron BA.4/5 were analyzed. The anti-spike IgG antibody titer was determined by endpoint titration. Neutralization titer (IC50) for all plasma samples was calculated. Antigen-specific T cells were measured by flow cytometry as a percentage of AIM+ (OX40+CD137+) CD4+ and (CD69+CD137+) CD8+ T cells after stimulation of PBMCs with peptide megapools. Findings: Of the participants, 18 (25%) were immunocompromised suffering cancer (ALL, lymphoma, sarcoma, hepatoblastoma), Inborn Errors of Immunity (IgA deficiency, X-linked agammaglobulinemia, common variable immunodeficiency) and LES under treatment with steroids. Almost all children remained seropositive and there were no differences in the titer of anti-spike IgG antibodies between healthy and immunocompromised children for any dose of the COVID-19 vaccines. Plasma neutralizing activity was significantly higher in healthy compared to immunocompromised children after the 3rd dose [1066 (434-1261) vs 135 (31-813), median (IQR) against Wuhan (p