The impact and cost-effectiveness of controlling cholera through the use of oral cholera vaccines in urban Bangladesh: A disease modeling and economic analysis.

Ashraful Islam Khan,Denise Deroeck,Ann Levin,Mohammad Ali,Jahangir A M Khan,Firdausi Qadri,Md Taufiqul Islam,Abdur Razzaque Sarker,Muhammad Shariful Islam,Dobromir T Dimitrov,John D Clemens,Dennis L Chao,Mathieu Maheu-Giroux

doi:10.1371/journal.pntd.0006652

Abstract

BackgroundCholera remains an important public health problem in major cities in Bangladesh, especially in slum areas. In response to growing interest among local policymakers to control this disease, this study estimated the impact and cost-effectiveness of preventive cholera vaccination over a ten-year period in a high-risk slum population in Dhaka to inform decisions about the use of oral cholera vaccines as a key tool in reducing cholera risk in such populations.Methodology/Principal findingsAssuming use of a two-dose killed whole-cell oral cholera vaccine to be produced locally, the number of cholera cases and deaths averted was estimated for three target group options (1–4 year olds, 1–14 year olds, and all persons 1+), using cholera incidence data from Dhaka, estimates of vaccination coverage rates from the literature, and a dynamic model of cholera transmission based on data from Matlab, which incorporates herd effects. Local estimates of vaccination costs minus savings in treatment costs, were used to obtain incremental cost-effectiveness ratios for one- and ten-dose vial sizes. Vaccinating 1–14 year olds every three years, combined with annual routine vaccination of children, would be the most cost-effective strategy, reducing incidence in this population by 45% (assuming 10% annual migration), and costing was $823 (2015 USD) for single dose vials and $591 (2015 USD) for ten-dose vials per disability-adjusted life year (DALY) averted. Vaccinating all ages one year and above would reduce incidence by >90%, but would be 50% less cost-effective ($894–1,234/DALY averted). Limiting vaccination to 1–4 year olds would be the least cost-effective strategy (preventing only 7% of cases and costing $1,276-$1,731/DALY averted), due to the limited herd effects of vaccinating this small population and the lower vaccine efficacy in this age group.Conclusions/SignificanceProviding cholera vaccine to slum populations in Dhaka through periodic vaccination campaigns would significantly reduce cholera incidence and inequities, and be especially cost-effective if all 1–14 year olds are targeted.

Highlights

The Ganges River Delta and Bay of Bengal, including Bangladesh, are considered the birthplace of cholera and the origin of six of the seven cholera pandemics recorded in modern times[1]
While oral cholera vaccines are increasingly being used in the past few years, mainly to curtail or preempt cholera outbreaks, they have yet to be used on a large scale to control endemic cholera in a high-burden country like Bangladesh
This study examines the potential impact on disease and value of vaccinating slum dwellers in Dhaka, who are among those at highest-risk of getting the disease

Summary

Introduction

The Ganges River Delta and Bay of Bengal, including Bangladesh, are considered the birthplace of cholera and the origin of six of the seven cholera pandemics recorded in modern times[1]. While national population-based estimates of cholera incidence are lacking in Bangladesh, the perception among local experts is that cholera is increasingly becoming an urban disease. Based on long-term systematic laboratory testing of 2% of all diarrheal patients presenting at the icddr,b (International Centre for Diarrhoeal Disease Research, Bangladesh) hospital in Dhaka (locally known as the “cholera hospital”), this hospital provides care and treatment to approximately 140,000 patients of all ages in each year[2]. During major floods in 2004, 2007 and 2009, icddr,b saw an estimated 30,000 or more cholera cases annually and V. cholerae overtook rotavirus and ETEC as the main pathogen found among patients with severe diarrhea presenting at the hospital[3]. Cholera remains an important public health problem in major cities in Bangladesh, especially in slum areas. In response to growing interest among local policymakers to control this disease, this study estimated the impact and cost-effectiveness of preventive cholera vaccination over a ten-year period in a high-risk slum population in Dhaka to inform decisions about the use of oral cholera vaccines as a key tool in reducing cholera risk in such populations

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Results

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Conclusion