Abstract
BACKGROUND: Severe infectious diseases remain a preventable cause of adolescent mortality worldwide, yet global evidence focused on adolescence as a distinct life-course stage-and its vulnerability to health system disruption-remains limited. We examined long-term mortality rate trends, cause composition, and COVID-19-related changes among adolescents compared with late childhood. METHODS: We analyzed Global Burden of Disease 2023 mortality estimates from 1990 to 2023 for six acute severe infectious causes: lower respiratory infections, meningitis, encephalitis, diarrhoeal diseases, typhoid/paratyphoid fever, and COVID-19. Analyses focused on adolescents aged 10-19 years, with children aged 5-9 years as a comparator. Mortality rates (per 100,000 population) were the primary metric. Trends were quantified using estimated annual percentage change (EAPC), and pre-COVID, COVID peak, and post-COVID periods were compared across Socio-demographic Index (SDI) categories. RESULTS: From 1990 to 2023, mortality rates declined globally across all age groups; however, reductions among adolescents were consistently slower than those among children aged 5-9 years (EAPC -2.27% vs. -3.55% per year). Diarrhoeal diseases and typhoid/paratyphoid fever exhibited the steepest long-term declines, whereas lower respiratory infections and meningitis demonstrated slower reductions and maintained a substantial share of adolescent mortality risk. During the COVID-19 peak, mortality rates modestly increased among adolescents, while children continued their gradual decline. Mortality rates remained highest in low-SDI settings. CONCLUSIONS: Despite substantial global progress, severe infectious diseases continue to impose significant and inequitable mortality risk among adolescents. The persistence of a concentrated cause profile and the amplification of mortality during system disruption underscore adolescence as a vulnerable life-course stage requiring sustained prevention and resilient acute care systems.