Evaluating the costs of cholera illness and cost-effectiveness of a single dose oral vaccination campaign in Lusaka, Zambia

Introduction
In 2016, for the very first time, the Ministry of Health in Zambia implemented a reactive outbreak response to control the spread of cholera and vaccinated at-risk populations with a single dose of Shancol—an oral cholera vaccine (OCV). This study aimed to assess the costs of cholera illness and determine the cost-effectiveness of the 2016 vaccination campaign.
Methodology
From April to June 2017, we conducted a retrospective cost and cost-effectiveness analysis in three peri-urban areas of Lusaka. To estimate costs of illness from a household perspective, a systematic random sample of 189 in-patients confirmed with V. cholera were identified from Cholera Treatment Centre registers and interviewed for out-of-pocket costs. Vaccine delivery and health systems costs were extracted from financial records at the District Health Office and health facilities. The cost of cholera treatment was derived by multiplying the subsidized cost of drugs by the quantity administered to patients during hospitalisation. The cost-effectiveness analysis measured incremental cost-effectiveness ratio—cost per case averted, cost per life saved and cost per DALY averted—for a single dose OCV.
Results
The mean cost per administered vaccine was US$1.72. Treatment costs per hospitalized episode were US$14.49–US$18.03 for patients ≤15 years old and US$17.66–US$35.16 for older patients. Whereas households incurred costs on non-medical items such as communication, beverages, food and transport during illness, a large proportion of medical costs were borne by the health system. Assuming vaccine effectiveness of 88.9% and 63%, a life expectancy of 62 years and Gross Domestic Product (GDP) per capita of US$1,500, the costs per case averted were estimated US$369–US$532. Costs per life year saved ranged from US$18,515–US$27,976. The total cost per DALY averted was estimated between US$698–US$1,006 for patients ≤15 years old and US$666–US$1,000 for older patients.
Conclusion
Our study determined that reactive vaccination campaign with a single dose of Shancol for cholera control in densely populated areas of Lusaka was cost-effective.

引言
2016年，赞比亚卫生部首次实施反应性暴发应对措施以控制霍乱传播，并为高危人群接种单剂次Shancol口服霍乱疫苗（oral cholera vaccine，OCV）。本研究旨在评估霍乱疾病的相关成本，并分析2016年该疫苗接种运动的成本效益。

研究方法
2017年4月至6月，我们在卢萨卡的3个城郊区域开展了回顾性成本与成本效益分析。为从家庭视角估算疾病相关成本，研究团队通过系统随机抽样，从霍乱治疗中心的登记记录中筛选出189名经实验室确诊感染霍乱弧菌（V. cholera）的住院患者，并对其开展访谈以获取自付费用数据。疫苗接种实施及卫生系统成本数据则提取自地区卫生办公室与各级医疗机构的财务档案。霍乱治疗成本通过将药品补贴单价乘以患者住院期间的用药总量计算得出。本研究的成本效益分析针对单剂次口服霍乱疫苗，测算增量成本效益比——包括每避免1例病例的成本、每挽救1条生命的成本以及每避免1个伤残调整寿命年（Disability-Adjusted Life Year，DALY）的成本。

研究结果
每剂次接种疫苗的平均成本为1.72美元。15岁及以下住院患者的单次住院治疗成本为14.49美元至18.03美元，15岁以上患者则为17.66美元至35.16美元。尽管患病期间家庭需承担通讯、饮品、食品及交通等非医疗开支，但绝大多数医疗成本由卫生系统承担。假设疫苗有效性分别为88.9%与63%，人群预期寿命为62岁，人均国内生产总值（Gross Domestic Product，GDP）为1500美元，则每避免1例病例的成本估算区间为369美元至532美元。每挽救1个生命年的成本区间为18515美元至27976美元。每避免1个DALY的总成本，15岁及以下患者估算区间为698美元至1006美元，15岁以上患者则为666美元至1000美元。

研究结论
本研究证实，在卢萨卡人口稠密区域开展的单剂次Shancol口服霍乱疫苗反应性接种运动用于霍乱防控，具备成本效益。