Abstract
Although the burden of influenza is often discussed in the context of historical pandemics and the threat of future pandemics, every year a substantial burden of lower respiratory tract infections (LRTIs) and other respiratory conditions (like chronic obstructive pulmonary disease) are attributable to seasonal influenza. The Global Burden of Disease Study (GBD) 2017 is a systematic scientific effort to quantify the health loss associated with a comprehensive set of diseases and disabilities. In this article, we focus on LRTIs that can be attributed to influenza.
Methods
We modeled the LRTI incidence, hospitalizations, and mortality attributable to influenza for every country and selected subnational locations by age and year from 1990 to 2017 as part of GBD 2017. We used a counterfactual approach that first estimated the LRTI incidence, hospitalizations, and mortality and then attributed a fraction of those outcomes to influenza.
Findings
Influenza LRTI was responsible for an estimated 145,000 (95% uncertainty interval [UI] 99,000–200,000) deaths among all ages in 2017. The influenza LRTI mortality rate was highest among adults older than 70 years (16.4 deaths per 100,000 [95% UI 11.6–21.9]), and the highest rate among all ages was in eastern Europe (5.2 per 100,000 population [95% UI 3.5–7.2]). We estimated that influenza LRTIs accounted for 9,459,000 (95% UI 3,709,000–22,935,000) hospitalizations due to LRTIs and 81,536,000 hospital days (24,330,000–259,851,000). We estimated that 11.5% (95% UI 10.0–12.9) of LRTI episodes were attributable to influenza, corresponding to 54,481,000 (38,465,000–73,864,000) episodes and 8,172,000 severe episodes (5,000,000–13,296,000).
Interpretation
This comprehensive assessment of the burden of influenza LRTIs shows the substantial annual effect of influenza on global health. Although preparedness planning will be important for potential pandemics, health loss due to seasonal influenza LRTIs should not be overlooked, and vaccine use should be considered. Efforts to improve influenza prevention measures are needed.