MMR Vaccine — Maurice Hilleman (1971)

Maurice Hilleman’s MMR vaccine, introduced in 1971, remains the most impactful combination vaccine ever developed, preventing an estimated 21 million deaths since 2000 alone. By merging three separate shots into one, it streamlined global immunization and reduced healthcare costs by 40% compared to administering each vaccine individually. The MMR vaccine outperforms the BCG tuberculosis vaccine (#7) in terms of direct mortality reduction in children, given its near-universal efficacy against measles. It continues to serve as the backbone of childhood immunization programs worldwide, with over 700 million doses distributed annually, underscoring its unmatched role in public health.