Global burden of lower respiratory infections and aetiologies, 1990–2023: a systematic analysis for the Global Burden of Disease Study 2023

Critical opinion

The Global Burden of Disease 2023 analysis shows that lower respiratory infections (LRIs) remain the leading infectious cause of death worldwide. The study’s strengths include its comprehensive global, regional, and national estimates over three decades, rigorous integration of large empirical mortality datasets, and explicit attribution of LRI burden to a wide panel of bacterial, viral, and fungal pathogens, which clarifies priority targets for vaccination, treatment, and surveillance. The modelling remains heavily dependent on assumptions and heterogeneous data quality from low‑resource settings, which may mask sub‑national heterogeneity and health‑system bottlenecks that are crucial for policy. Moreover, while antimicrobial resistance is highlighted, the translation of these estimates into concrete stewardship, vaccine investment, and health‑system strengthening strategies is left largely implicit, underscoring that the main constraints to reducing LRI mortality are political and financial rather than analytic.

Summary

This comprehensive Global Burden of Disease (GBD) 2023 analysis evaluates the incidence, mortality, and disability‑adjusted life years (DALYs) attributable to lower respiratory infections (LRIs) across 204 countries from 1990 through 2023. LRIs remain the leading infectious cause of death worldwide, with 2.50 million deaths and 98.7 million DALYs in 2023. Despite decades of progress in pediatric vaccination and improvements in primary healthcare, the disease burden persists—especially among children younger than 5 years and adults aged 70 years and older.

A major strength of the 2023 analysis is its inclusion of 26 pathogens, expanding on the 18 modelled in GBD 2021. Eleven newly modeled pathogens—most notably non-tuberculous mycobacteria and Aspergillus species—collectively accounted for approximately 22% of LRI deaths in 2023. This more granular pathogen-specific modelling improves understanding of the changing aetiological landscape, especially among immunocompromised and aging populations, where fungal and atypical bacterial infections are rising.

Epidemiological trends

Globally, mortality from LRIs has declined since 1990, but the pace of decline has slowed significantly in the past decade. Among children under 5, mortality fell by 33.4% from 2010 to 2023, yet the 2023 global mortality rate (94.8 per 100,000) remains substantially above the Global Action Plan for the Prevention and Control of Pneumonia and Diarrhoea (GAPPD) target of fewer than 60 deaths per 100,000. While 129 of 204 countries have achieved this benchmark, sub-Saharan Africa remains farthest from the goal due to inequities in vaccination coverage, healthcare access, malnutrition, and exposure to indoor and outdoor air pollution.

Adults aged 70 years and older continue to bear the highest mortality, with a rate of 231.6 per 100,000 in 2023—a modest 10.2% reduction since 2010. Population aging, immunosenescence, and comorbidity clustering (e.g., COPD, cardiovascular disease, diabetes) sustain high susceptibility despite the availability of pneumococcal and influenza vaccines. Yet adult vaccination rates remain low in many low‑ and middle-income countries (LMICs), partly due to underdeveloped policy frameworks and cost barriers.

Pathogen distribution

Streptococcus pneumoniae remained the leading cause of LRI deaths globally, responsible for 634,000 deaths (25.3% of all LRI deaths) in 2023, followed by Staphylococcus aureus and Klebsiella pneumoniae. This emphasizes the enduring significance of bacterial pneumonia even as viral and fungal pathogens gain relative prominence. Viral LRIs such as influenza and RSV remain major contributors, with RSV especially significant among young children and influenza among older adults. The lifting of COVID–19–related non-pharmaceutical interventions (NPIs) appears to have led to a resurgence of influenza circulation.

The expansion of pathogen-specific modelling reveals emerging threats: non-tuberculous mycobacteria accounted for 177,000 deaths (more than any newly modeled pathogen), and Aspergillus spp for nearly 68,000. These numbers are lower than some clinical estimates (e.g., 1.3 million Aspergillus deaths annually), owing to GBD’s attribution rules, which assign deaths to a single underlying cause.

Diagnostic and surveillance advances

The study emphasizes the growing role of next-generation sequencing (NGS) and multiplex PCR in improving etiologic detection. NGS can identify pathogens in up to 84% of cases compared with 27% using traditional culture methods, though cost remains a barrier in LMICs. Improved detection is essential for monitoring antimicrobial resistance and emerging pathogens.

Policy and intervention implications

Vaccination remains the most effective intervention for reducing pediatric LRI burden. Pneumococcal and Haemophilus influenzae type b (Hib) vaccines have averted an estimated 1.76 million childhood deaths in the past two decades. Yet the benefits remain unevenly distributed, with persistent gaps in coverage across Africa and parts of Asia.

RSV prevention represents the next frontier. Newly approved long-acting monoclonal antibodies and vaccines could substantially reduce child mortality but remain largely inaccessible in low-resource settings, where most RSV deaths occur.

Among adults, pneumococcal and influenza vaccines are underused in LMICs, despite evidence of cost-effectiveness for individuals over 50. Tailored immunization strategies based on serotype distribution and local epidemiology are urgently needed.

Strengths include vastly expanded pathogen modelling, use of updated mortality data from the 2020–2021 pandemic years, and incorporation of over 12 million pathogen isolates into the etiologic models.

Limitations include reliance on covariate-based estimates for countries lacking primary data, underestimation of viral contributions due to classification rules, and inability to fully capture regional pathogen heterogeneity.

By Health Literacy Asia