The GBD 2021 perspective: COVID-19's impact on diarrheal mortality and etiological trends, 1990-2021.

Introduction: Diarrheal diseases remain a leading cause of global mortality. While significant progress has been made in reducing diarrheal deaths, particularly among children under five, the COVID-19 pandemic introduced new dynamics through non-pharmaceutical interventions and healthcare disruptions. Understanding the evolving burden during this period is critical for guiding post-pandemic control strategies. Methods: Using data from the Global Burden of Disease Study 2021, we analyzed diarrhea-related deaths and age-standardized death rates (ASDRs) across 204 countries from 1990 to 2021. Estimated annual percentage changes (EAPCs) were calculated to assess temporal trends. Analyses were stratified by age, sex, socio-demographic index (SDI), and 13 major diarrheal pathogens. Results: Globally, diarrheal deaths declined from 1.26 million (95% UI: 0.90 to 1.72) in 2019 to 1.17 million (0.79 to 1.62) in 2021, with accelerated reduction during the pandemic (EAPC -5.10 vs -4.25 pre-pandemic). Adults >70 years emerged as the highest-risk group (100.75 deaths/100,000), surpassing children under five (51.72/100,000). Eastern Sub-Saharan Africa bore the heaviest burden (ASDR 59.99), while high-income North America showed the fastest pre-pandemic increase (EAPC 8.10). Rotavirus remained the leading cause (0.18 million deaths), though norovirus rose to second place (0.12 million). Pathogen distribution varied markedly by SDI, with Conclusions: Despite accelerated mortality reduction during COVID-19, persistent disparities highlight the dual challenge of pediatric and geriatric diarrheal burdens. Targeted strategies must combine expanded vaccination (particularly for rotavirus and emerging norovirus), SDI-adapted WASH interventions, and strengthened surveillance to address the shifting epidemiological landscape and achieve equitable control.