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

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.

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.

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 Clostridium difficile dominating in high-SDI regions (ASDR 0.53) and Cryptosporidium in low-SDI areas (ASDR 8.69). The Caribbean saw the most rapid pre-pandemic increase in cholera (EAPC 47.21). Notably, East Asia experienced increasing ASDRs for multiple pathogens during the pandemic, contrasting with global declines. SDI showed strong negative correlations with most pathogens (ρ<-0.8), except for Clostridium difficile (ρ=0.63).

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.