They play an essential role in B-cell development and long-term humoral immunity.28 While Esparcia-Pinedo and colleagues found no difference in circulating spike-specific Tfhs after primary vaccination,22 Tfhs have been shown to be reduced in both tonsils and in the circulation of children with DS,29 with a skewed CXCR3+ Tfh1 phenotype suggestive of poor B cell helper function.28 Additionally, the lower percentage of AIM+ CD4+ T cells in adults with DS after mRNA vaccination might result in less interactions with B cells, contributing to lower antibody titers. The gene discussed is CD69; the disease is Dravet syndrome.