XBB.1.5 RBD double-positive memory B cells (left) were analyzed for cross-reactivity with the Wuhan-Hu-1 (Wu) RBD (right). Memory B cells were obtained from peripheral blood collected from individuals 7-13 days (mean: 10 days) after receiving the XBB.1.5 S mRNA booster using flow cytometry. See also Figure S5.
