As these lines were written, the Covid-19 pandemic crisis was continuing to threaten countries around the globe. The worldwide consensus that physical distancing is an effective instrument for mitigating the spread of the virus has led policymakers to temporarily limit the freedom of movement of people between and within countries, cities, and even neighborhoods. These public health-related restrictions on human mobility yielded an unprecedented fragmentation of international and national food distribution systems. Focusing on food retailing - usually being modestly oligopolistic - we take a micro-economic perspective as we analyze the potential consequences this disruption has for the physical as well as for the economic access of households to food at the local level. As the mobility constraints implemented substantially reduced competition, we argue that food retailers might have been tempted to take advantage of the implied fragmentation of economic activity by exploiting their temporarily raised market power at the expense of consumers and farmers. We illustrate our point by providing empirical evidences of rising wholesale-retail as well as farm-retail price margins observed during the Covid-19 crisis. Subsequently, we review existing empirical approaches that can be used to quantify and decompose the micro-economic effects of crises on food demand and supply as well as the size and structure of the market, costs of trade, and economic welfare. The employment of such approaches facilitates policymakers’ understanding of micro-economic effects of public health-induced mobility restrictions on economic activity.

中文翻译：

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危机时期不完善的食品市场：供应链中断和分散对当地市场力量和城市脆弱性的经济后果

在撰写这些行文时，Covid-19 大流行危机继续威胁着全球各国。世界范围内的共识是，保持身体距离是减缓病毒传播的有效手段，这导致决策者暂时限制国家、城市甚至社区之间和内部的人员流动自由。这些与公共卫生相关的对人员流动性的限制导致国际和国家食品分配系统出现前所未有的碎片化。专注于食品零售——通常是适度的寡头垄断——我们从微观经济的角度分析这种破坏对当地家庭在物质和经济上获取食品的潜在影响。由于流动性限制大大减少了竞争，我们认为，食品零售商可能会试图利用经济活动隐含的碎片化优势，以牺牲消费者和农民为代价，利用他们暂时提升的市场力量。我们通过提供在 Covid-19 危机期间观察到的批发零售和农产品零售价格利润率上升的经验证据来说明我们的观点。随后，我们回顾了现有的实证方法，这些方法可用于量化和分解危机对粮食需求和供应以及市场规模和结构、贸易成本和经济福利的微观经济影响。采用此类方法有助于决策者了解公共卫生引起的流动性限制对经济活动的微观经济影响。