Moon Nahm, M.D., professor emeritus at UAB Department of Medicine and Director of the World Health Organization's Pneumococcal Serology Reference Laboratory at UAB, discusses his career in pneumococcal immunology. From uncovering the WU2 reference strain and other hidden serotypes to pioneering Multiplexed Opsono-Phagocytosis Assay (MOPA) to measure the functional activity of anti-pneumococcal antibodies, Nahm's contributions have facilitated development of advanced vaccines with broader protection and accessibility.