Jan M. Brauner et al: Inferring the effectiveness of government interventions against Covid-19, in Science 371 (February 2021) no. 6531, pp. 1-8, DOI: 10.1126/science.abd9338.
Governments are attempting to control the COVID-19 pandemic with nonpharmaceutical interventions (NPIs). However, the effectiveness of various NPIs at reducing transmission is poorly understood. The authors collected chronological data on the implementation of NPIs for several European and non-European countries between January and the end of May 2020.
They estimated the effectiveness of these NPIs, which range from limiting gathering size, business closures, and closures of educational institutions to stay-at-home orders. To do so, they used a Bayesian hierarchical model that links NPI implementation dates to national case and death counts and supported the results with extensive empirical validation. Closing all educational institutions, limiting gatherings to 10 people or less, and closing face-to-face businesses each reduced transmission considerably. The additional effect of stay-at-home orders was comparatively small.