Covid-19: Early evening curfews are not effective and may backfire

Background During the COVID-19 pandemic, some countries have introduced early evening curfews. Several studies try measure the effectiveness of such measures across different countries, but clear identification of effects is elusive. Objective We examined the impact of an early evening curfew on mobility by studying a shift in curfews from 9pm to 6pm in Greece. Data and Methods We took advantage of a natural experiment in Greece, where curfews shifted from 9pm to 6pm in one Region, but not in another. We followed a difference-in-differences econometric approach, where we compared trends in mobility in groceries and pharmacies as well as residential spaces before and after the introduction of the 6pm curfew, in the two regions. Results The relative difference in the time spent in groceries and pharmacies between the two regions before and after the intervention, is statistically insignificant [coeff: −9.95; 95%CI −44.358 to 24.458]. The relative increase in time spent at residential spaces after the 6pm curfew was only 4.625 percentage points [coeff: 4.625; 95%CI 1.412 to 7.838]. Conclusions We found that the 6pm instead of 9pm curfew in Athens led to a 4.63 percentage point relative increase in time spent at home and had no effect on time spent in groceries and pharmacies. Considering that this was a result of a 18.75% reduction in hours where people were allowed to leave home, it seems that the early evening curfew led to more crowding in indoor spaces – which may facilitate the spread of disease. Interventions should be based on a thorough analysis of human behaviour, that anticipates substitution of activities. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement No funding ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Secondary data, no ethics needed All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes The data are publicly available already,