Data set accompanying the publication "Preexisting memory CD4 T cells in naïve individuals confer robust immunity upon vaccination". In this study, we utilize high-throughput sequencing to profile the memory CD4 TCRβ repertoire and track vaccine-specific and epitope-specific TCRβ clonotypes following the de novo administration of hepatitis B (HepB) vaccine in healthy HepB-naïve individuals. The data set is comprised out of the following parts: repTCRb: Folder containing CD4+ TCR repertoire data from volunteers. Some of these samples are also available in ImmuneAccess (https://clients.adaptivebiotech.com/pub/deneuter-2018-cmvserostatus). peptideTCRab: Folder containing peptide-specific or peptide-pool-specific TCR data df_all: Meta and FC data for samples and volunteers freqCD154: CD154-based group definitions groups.csv: Group definitions used for classes