 This research examined the longitudinal dynamics of antibody immunity following heterologous SARS-CoV-2 breakthrough infection in six mRNA-vaccinated individuals. The authors found that cross-reactive serum-neutralizing antibodies and memory B-cells, MBCs, declined over time after breakthrough infection, while new Armacran BA.1-specific B-cells were generated. Additionally, public clone-dominant neutralizing antibodies predicted newly emerging Armacran sub-lineages, suggesting that antibody responses continue to shape SARS-CoV-2 evolution. This research suggests that heterologous SARS-CoV-2 variant exposure drives the evolution of B-cell memory, supporting the continued development of next-generation variant-based vaccines. This article was authored by Ching Zai Koku, Tyler N. Star, Pan Pan Ju, and others.