National, regional, and state-level burden of Streptococcus pneumoniae and Haemophilus influenzae type b disease in children in India: modelled estimates for 2000-15.

BACKGROUND

India accounts for a disproportionate burden of global childhood illnesses. To inform policies and measure progress towards achieving child health targets, we estimated the annual national and state-specific childhood mortality and morbidity attributable to Streptococcus pneumoniae and Haemophilus influenzae type b (Hib) between 2000 and 2015.

METHODS

In this modelling study, we used vaccine clinical trial data to estimate the proportion of pneumonia deaths attributable to pneumococcus and Hib. The proportion of meningitis deaths attributable to each pathogen was derived from pathogen-specific meningitis case fatality and bacterial meningitis case data from surveillance studies. We applied these proportions to modelled state-specific pneumonia and meningitis deaths from 2000 to 2015 prepared by the WHO Maternal and Child Epidemiology Estimation collaboration (WHO/MCEE) on the basis of verbal autopsy studies from India. The burden of clinical and severe pneumonia cases attributable to pneumococcus and Hib was ascertained with vaccine clinical trial data and state-specific all-cause pneumonia case estimates prepared by WHO/MCEE by use of risk factor prevalence data from India. Pathogen-specific meningitis cases were derived from state-level modelled pathogen-specific meningitis deaths and state-level meningitis case fatality estimates. Pneumococcal and Hib morbidity due to non-pneumonia, non-meningitis (NPNM) invasive syndromes were derived by applying the ratio of pathogen-specific NPNM cases to pathogen-specific meningitis cases to the state-level pathogen-specific meningitis cases. Mortality due to pathogen-specific NPNM was calculated with the ratio of pneumococcal and Hib meningitis case fatality to pneumococcal and Hib meningitis NPNM case fatality. Census data from India provided the population at risk.

FINDINGS

Between 2000 and 2015, estimates of pneumococcal deaths in Indian children aged 1-59 months fell from 166 000 (uncertainty range [UR] 110 000-198 000) to 68 700 (44 600-86 000), while Hib deaths fell from 82 600 (52 300-112 000) to 15 600 (9800-21 500), representing a 58% (UR 22-78) decline in pneumococcal deaths and an 81% (59-91) decline in Hib deaths. In 2015, national mortality rates in children aged 1-59 months were 56 (UR 37-71) per 100 000 for pneumococcal infection and 13 (UR 8-18) per 100 000 for Hib. Uttar Pradesh (18 900 [UR 12 300-23 600]) and Bihar (8600 [5600-10 700]) had the highest numbers of pneumococcal deaths in 2015. Uttar Pradesh (9300 [UR 5900-12 700]) and Odisha (1100 [700-1500]) had the highest numbers of Hib deaths in 2015. Less conservative assumptions related to the proportion of pneumonia deaths attributable to pneumococcus indicate that as many as 118 000 (UR 69 000-140 000) total pneumococcal deaths could have occurred in 2015 in India.

INTERPRETATION

Pneumococcal and Hib mortality have declined in children aged 1-59 months in India since 2000, even before nationwide implementation of conjugate vaccines. Introduction of the Hib vaccine in several states corresponded with a more rapid reduction in morbidity and mortality associated with Hib infection. Rapid scale-up and widespread use of the pneumococcal conjugate vaccine and sustained use of the Hib vaccine could help accelerate achievement of child survival targets in India.

FUNDING

Bill & Melinda Gates Foundation.