Abstract
BACKGROUND: Upper respiratory infections (URIs) impose a substantial global disease burden; however, the evolving epidemiological landscape, specifically for adolescents and young adults (aged 10-24 years), remains obscured by aggregate analyses. Given that this demographic represents a critical phase for human capital development, understanding the long-term trends of URIs is vital for optimizing resource allocation and intervention strategies. This study aimed to quantify the global, regional, and national burden of URIs in this pivotal group from 1990 to 2021 and project trends to 2035, informing targeted public health policies. METHODS: Data were derived from the Global Burden of Disease (GBD) Study 2021. Annual incidence, mortality, and disability-adjusted life years (DALYs) were analyzed across three age subgroups (10-14, 15-19, and 20-24 years). Temporal trends in age-standardized incidence rate (ASIR), age-standardized mortality rate (ASMR), and age-standardized DALYs rate (ASDR) were evaluated using estimated annual percentage changes (EAPC). The average annual percent change (AAPC) summarized the overall trend. A Bayesian age-period-cohort (BAPC) model was employed to forecast disease burden through 2035. Analyses were stratified by sex, region, and socio-demographic index (SDI). RESULTS: From 1990 to 2021, global ASIR declined slightly (EAPC =-0.16%), while ASMR (-1.69%) and ASDR (-0.26%) showed more substantial reductions. The 10-14 years age group consistently had the highest incidence and DALYs burden, with the slowest mortality decline (EAPC =-1.34%), whereas the 20-24 years age group demonstrated the most rapid improvement. Males experienced steeper mortality reductions (-2.25%) than females (-1.11%). Contrasting global improvements, the high-middle SDI region exhibited a significant upward trend in ASIR (EAPC =0.02%), and increases were also observed in the Caribbean and parts of sub-Saharan Africa. Projections indicate a continued decline in rates but a paradoxical rise in absolute case numbers among older adolescents (15-24 years) by 2035. CONCLUSIONS: While the global mortality and DALYs burden of URIs in adolescents and young adults has improved, incidence remains persistently high, particularly in the 10-14 years age group and high-middle SDI regions. The projected rise in case numbers among older cohorts suggests emerging challenges, potentially linked to immunity gaps. Future strategies must prioritize targeted interventions in high-burden demographics and environmental pollution mitigation.