Pediatr Neonatol. 2026 Jul 21:S1875-9572(26)00112-9. doi: 10.1016/j.pedneo.2026.05.005. Online ahead of print.
ABSTRACT
BACKGROUND: Immunogenicity following an additional (third) COVID-19 vaccine dose in children receiving immunosuppressive therapy remains insufficiently characterized.
METHODS: We enrolled immunosuppressed children with hematological malignancies, nephrotic syndrome (NS), or inflammatory bowel disease (IBD) who had completed a two-dose primary series of mRNA-1273 or BNT162b2 at least 150 days prior to enrollment. Humoral and cellular immune responses were assessed before and after an additional dose and compared with responses in healthy children one month after primary vaccination.
RESULTS: In children receiving immunosuppressive therapy (n = 7), the additional dose resulted in a 1.50-fold increase in anti-spike IgG levels and a modest 1.14-fold increase in cellular immune responses. Children with hematological cancers (n = 2) showed increases in both humoral and cellular immune responses. Despite the additional dose, anti-spike IgG levels in the immunosuppressed group (geometric mean concentration = 895.62 BAU/mL) remained lower than those in healthy controls (2454.56 BAU/mL; n = 14), although the difference was not statistically significant, while levels in the hematological cancer group were substantially lower (16.26 BAU/mL). Cellular immune responses also remained reduced in both the immunosuppressed group (69.73 SFU/2 × 105 PBMCs) and the hematological cancer group (17.89 SFU/2 × 105 PBMCs) compared with healthy controls (112.26 SFU/2 × 105 PBMCs). Neutralizing antibody titers against the BA.2 variant increased by 2.08-fold in the immunosuppressed group and by 18.12-fold in the hematological cancer group.
CONCLUSIONS: Although an additional mRNA-1273 dose was associated with increased humoral and cellular immune responses in children with hematological cancers and enhanced humoral responses in immunosuppressed children, the overall magnitude of response was limited. Immunogenicity following the additional dose was modest, and the clinical benefit of an additional dose in children with NS, IBD, or hematological cancers remains uncertain.
PMID:42562753 | DOI:10.1016/j.pedneo.2026.05.005
