Among tool kits to combat the coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2, school closures are one of the most frequent non-pharmaceutical interventions. However, school closures bring about substantial costs, such as learning loss. To date, studies have not reached a consensus about the effectiveness of these policies at mitigating community transmission, partly because they lack rigorous causal inference. Here we assess the causal effect of school closures in Japan on reducing the spread of COVID-19 in spring 2020. By matching each municipality with open schools to a municipality with closed schools that is the most similar in terms of potential confounders, we can estimate how many cases the municipality with open schools would have had if it had closed its schools. We do not find any evidence that school closures in Japan reduced the spread of COVID-19. Our null results suggest that policies on school closures should be reexamined given the potential negative consequences for children and parents.

Standard-Nutzungsbedingungen:Die Dokumente auf EconStor dürfen zu eigenen wissenschaftlichen Zwecken und zum Privatgebrauch gespeichert und kopiert werden.Sie dürfen die Dokumente nicht für öffentliche oder kommerzielle Zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen.Sofern die Verfasser die Dokumente unter Open-Content-Lizenzen (insbesondere CC-Lizenzen) zur Verfügung gestellt haben sollten, gelten abweichend von diesen Nutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte. Terms of use: Documents in EconStor may AbstractIn this article, we quantitatively analyze changes in the size distribution of municipal jurisdictions in Japan by using their rank-size distribution to capture the changes. In Japan, the central government sometimes enacts large-scale municipal mergers, aimed at creating municipalities of a certain size. Japan's local governance policy allocates tax revenues to municipalities based on the financial shortages of each municipality, which is designed to ensure financial equality among municipalities so that the central government can evenly maintain public services, especially in rural areas. Thus, if the central government eases population discrepancy among municipalities and creates a large number of uniformly sized municipalities, then the central government can reduce subsidies to local governments. The government's previous policies on municipal mergers were enacted to foster this sort of efficiency. We examine changes in the distribution of municipal jurisdiction sizes to determine the actual effect of municipal merger policies. Our results show that the discrepancy in population among municipalities was once leveled by the great municipal mergers of the 1950s Showa era.

We examined the phenomenon of fewer new confirmed cases on Monday in Japan, which we refer to as the Monday effect. In Japan, prefectures aggregate and announce the number of daily confirmed cases. We analyzed the impact of this effect in each prefecture. The effect is mainly found in prefectures with populations of 2 million or more. This effect is also constantly observed in the three major metropolitan areas in Japan. However, the magnitude of the observed effect is uncorrelated with both the number of positives per 1,000 people and the population size. Our results suggest that the reporting delay occurs in prefectures above a specific size, but the magnitude of the delay differs among prefectures. We consider two possible explanations for this effect: 1) delays caused by the administrative system. 2) fewer tests are conducted on the previous day. Our results indicate that delays are caused by the administrative system in some prefectures and that some prefectures with larger populations are less likely to conduct screenings on holidays.

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As COVID-19 spread in 2020, most countries shut down schools in the hopes of slowing the pandemic. Yet, studies have not reached a consensus about the effectiveness of these policies partly because they lack rigorous causal inference. Our study aims to estimate the causal effects of school closures on the number of confirmed cases. To do so, we apply matching methods to municipal-level data in Japan. We do not find that school closures caused a reduction in the spread of the coronavirus. Our results suggest that policies on school closures should be reexamined given the potential negative consequences for children and parents.