Wahl B, et al. - Authors monitored global and regional progress towards improving child health and informed national policies for disease prevention and treatment by preparing global, regional, and national disease burden estimates for these pathogens in children from 2000 to 2015. Results demonstrated an association of the widespread use of Hib vaccine and the recent introduction of pneumococcal conjugate vaccine (PCV) in countries with high child mortality with reductions in Haemophilus influenzae type b (Hib) and pneumococcal cases and deaths. The fraction of pneumonia deaths attributable to pneumococcus largely drive the uncertainties in the burden of pneumococcal disease.

Methods

• Experts applied pneumococcal and Hib cause-specific proportions to estimate pathogen-specific deaths and cases using WHO and Maternal and Child Epidemiology Estimation collaboration country-specific estimates of pneumonia and meningitis mortality and pneumonia morbidity from 2000 to 2015.
• They derived the summary estimates of the proportion of pneumonia deaths and cases attributable to these pathogens from four Hib vaccine and six PCV efficacy and effectiveness study values.
• Bacterial meningitis aetiology and adjusted pathogen-specific meningitis case–fatality data derived the proportion of meningitis deaths due to each pathogen.
• From modelled pathogen-specific meningitis deaths and literature-derived case–fatality estimates, pneumococcal and Hib meningitis cases were inferred.
• They estimated the cases of pneumococcal and Hib syndromes other than pneumonia and meningitis using the ratio of pathogen-specific non-pneumonia, non-meningitis cases to pathogen-specific meningitis cases from the literature.
• They accounted for annual HIV infection prevalence, access to care, and vaccine use.

Results

• Findings suggested that there were 294,000 pneumococcal deaths (uncertainty range [UR] 192,000–366,000) and 29,500 Hib deaths (18,400–40,700) in HIV-uninfected children aged 1–59 months in 2015.
• As per data, they estimated an additional 23,300 deaths (15,300–28,700) associated with pneumococcus and fewer than 1000 deaths associated with Hib to have occurred in children infected with HIV.
• A decline in the pneumococcal deaths by 51% (7–74) and Hib deaths by 90% (78–96) was seen from 2000 to 2015.
• Pneumonia was seen in most children who died of pneumococcus (81%) and Hib (76%).
• Results demonstrated that less conservative assumptions result in pneumococcccal death estimates that could be as high as 515,000 deaths (302,000–609,000) in 2015.
• Researchers noted occurrence of approximately 50% of all pneumococcal deaths in 2015 in four countries in Africa and Asia: India (68,700 deaths, UR 44,600–86,100), Nigeria (49,000 deaths, 32,400–59,000), the Democratic Republic of the Congo (14,500 deaths, 9300–18,700), and Pakistan (14,400 deaths, 9700–17,000]).
• In 2015, India (15,600 deaths, 9800–21,500), Nigeria (3600 deaths, 2200–5100), China (3400 deaths, 2300–4600), and South Sudan (1000 deaths, 600–1400) had the greatest number of Hib deaths.
• In children, 3·7 million episodes (UR 2·7 million–4·3 million) of severe pneumococcus and 340,000 episodes (196,000–669,000) of severe Hib globally were estimated in 2015.