Humoral and cellular response to the COVID-19 vaccine in immunocompromised children

RUSSO, CONSTANZA; SEERY, VANESA; URANGA, MACARENA; RAIDEN, SILVINA; ALGIERI, SILVIA; DE CARLI, NORBERTO; BORDA, MAURICIO; OTERO, ADRIÁN; SANANEZ, INÉS; ALBISTUR, MF; HEINITZ, L; MARCO DEL PONT, M; PARDINI, M; BUDANO, G; ALVAREZ, LAURA; SIMAZ, NANCY; MERHAR, C; QUINTANA, MC; GARBINI, C; AEDO PORTELA, LF; VIDAL TORDOYA, F; DACONTE BARRIOS, GZ; SALCEDO PEREIRA, MY; FERRERO, FERNANDO; GEFFNER, JORGE; ARRUVITO, LOURDES

San Luis

Congreso; Reunión Anual SAI 2023; 2023

SAI

Background:Developing an optimal vaccine-induced anti-SARS-CoV-2 protectiveimmunity depends on a fully competent immune system. Some evidencewas gathered on the effects of vaccination outcomes inimmunocompromised adults. But few observations have been maderegarding immunocompromised children in terms of strength andperdurability. We aimed to determine the humoral and cellular immuneresponse to the 2ndand 3rdCOVID-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 mRNAvaccines). Themedian time since the 2nddose until sampling was 462 days and since the 3rddose was 300 days. Plasmalevels of anti-spike IgG antibodies, neutralizing activity, andantigen-specific T cells against the ancestral variant (Wuhan) andthe variant of concern Omicron BA.4/5 were analyzed. Theanti-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 apercentage 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 variableimmunodeficiency) and LES under treatment with steroids. Almost allchildren remained seropositive and there were no differences in thetiter of anti-spike IgG antibodies between healthy andimmunocompromised children for any dose of the COVID-19 vaccines.Plasmaneutralizing activity was significantly higher in healthy compared toimmunocompromised children after the 3rddose [1066 (434-1261) vs 135 (31-813), median (IQR) against Wuhan(p<0.05) and 249 (111-481) vs 16 (1-93) against Omicron(p<0.001)]. Consequently, we calculated an anti-spike IgGneutralization potency index (IC50/IgG) for each patient and foundthat immunocompromised children had a significantly lower indexagainst Omicron (p<0.001). Nearly50% of children had detectable CD4+T cell memory after 2 or 3 doses, but the proportion of childrenshowing CD8+specific T cells was about 20%. There were no differences in thespecific T cell response between groups. Interpretation:Although most immunocompromised children mount a long-term humoralmemory immune response to the first series COVID-19 vaccine, thespecific T cell-response has a distinct kinetic. Understanding thecomplexities of immune memory to COVID-19 vaccines is key to informvaccination strategies in the pediatric population.p { line-height: 115%; text-align: left; orphans: 2; widows: 2; margin-bottom: 0.25cm; direction: ltr; background: transparent }