This study finds that boys who lived through the deadly 1918 influenza pandemic, especially in high-exposure cities, died earlier as adults than those who didn’t. Using census and death records, research shows that being exposed to the flu pandemic in early childhood reduced life expectancy by up to 11 months. The long-term effects are linked to drops in education and socioeconomic status, showing how early-life crises can cast a shadow over an entire lifetime. These findings underscore the lifelong stakes of public health crises and the value of early interventions for children during pandemics.