Application of single-cell B cell receptor sequencing (scBCR-seq) to young mice has shown that individual low- and high-affinity B cell clones can give rise to both memory and plasma cells;105 whether this holds true in aged mice is an unanswered but important question as bulk BCR-seq from humans has shown that elderly subjects have reduced IgH diversity pre- and post-influenza vaccination compared to young subjects106. The gene discussed is BCR; the disease is influenza.