Vaccination scenarios.

Vaccination is considered as the main tool for the Global Control and Eradication Strategy for peste des petits ruminants (PPR), and the efficacity of the PPR-vaccine in conferring long-life immunity has been established. Despite this, previous studies asserted that vaccination can be expensive and consequently, the effectiveness of disease control may not necessarily translate to overall profit for farmers. Also, the consequences of PPR control on socioeconomic indicators like food and nutrition security at a macro-national level have not been explored thoroughly. Therefore, this study seeks to assess ex-ante the impact of PPR control strategies on farm-level profitability and the socioeconomic consequences concerning food and nutrition security at a national level in Senegal. A bi-level system dynamics model, compartmentalised into five modules consisting of integrated production-epidemiological, economics, disease control, marketing, and policy modules, was developed with the STELLA Architect software, validated, and simulated for 30 years at a weekly timestep. The model was parameterised with data from household surveys from pastoral areas in Northern Senegal and relevant existing data. Nine vaccination scenarios were examined considering different vaccination parameters (vaccination coverage, vaccine wastage, and the provision of government subsidies). The findings indicate that compared to a no-vaccination scenario, all the vaccination scenarios for both 26.5% (actual vaccination coverage) and 70% (expected vaccination coverage) resulted in statistically significant differences in the gross margin earnings and the potential per capita consumption for the supply of mutton and goat meat. At the prevailing vaccination coverage (with or without the provision of government subsidies), farm households will earn an average gross margin of $69.43 (annually) more than without vaccination, and the average per capita consumption for mutton and goat meat will increase by 1.13kg/person/year. When the vaccination coverage is increased to the prescribed threshold for PPR eradication (i.e., 70%), with or without the provision of government subsidies, the average gross margin earnings would be $72.23 annually and the per capita consumption will increase by 1.23kg/person/year compared to the baseline (without vaccination). This study’s findings offer an empirical justification for a sustainable approach to PPR eradication. The information on the socioeconomic benefits of vaccination can be promoted via sensitization campaigns to stimulate farmers’ uptake of the practice. This study can inform investment in PPR control.

小反刍兽疫（peste des petits ruminants, PPR）全球防控与根除策略中，疫苗接种被视作核心手段，PPR疫苗可诱导长期免疫力的有效性已得到证实。尽管如此，既往研究表明疫苗接种成本高昂，由此疫病防控的成效未必能转化为农户的整体收益。此外，PPR防控对宏观国家层面粮食与营养安全等社会经济指标的影响尚未得到充分探究。本研究旨在事前评估PPR防控策略对塞内加尔农场层面盈利能力的影响，以及该国层面粮食与营养安全相关的社会经济后果。研究依托STELLA Architect软件开发了双层系统动力学模型，该模型划分为生产-流行病学、经济学、疫病防控、市场营销与政策共5个集成模块，并以塞内加尔北部牧区农户调查数据及现有相关数据完成参数化校准，随后开展模型验证，并以周为时间步长进行了30年的模拟仿真。本研究设置9种疫苗接种情景，考量不同接种参数（接种覆盖率、疫苗损耗率及政府补贴供给情况）。结果显示，相较于无疫苗接种情景，无论是26.5%（实际接种覆盖率）还是70%（预期接种覆盖率）的接种情景，绵羊肉与山羊肉供给的毛利润收益及人均潜在消费量均存在统计学意义上的显著差异。在当前接种覆盖率水平下（无论是否配套政府补贴），农户年均毛利润较无接种情景平均高出69.43美元，绵羊肉与山羊肉的人均年消费量将提升1.13千克/人。当接种覆盖率提升至PPR根除的规定阈值（即70%）时，无论是否配套政府补贴，相较于无接种的基准情景，农户年均毛利润收益将达到72.23美元，人均消费量将提升1.23千克/人。本研究结果为PPR根除的可持续路径提供了实证依据。可通过宣传推广活动普及疫苗接种的社会经济收益相关信息，以激发农户对该防控措施的采纳意愿。本研究可为PPR防控领域的投资决策提供参考。