Social distancing is the core policy response to coronavirus disease 2019 (COVID-19). But, as federal, state and local governments begin opening businesses and relaxing shelter-in-place orders worldwide, we lack quantitative evidence on how policies in one region affect mobility and social distancing in other regions and the consequences of uncoordinated regional policies adopted in the presence of such spillovers. To investigate this concern, we combined daily, county-level data on shelter-in-place policies with movement data from over 27 million mobile devices, social network connections among over 220 million Facebook users, daily temperature and precipitation data from 62,000 weather stations, and county-level census data on population demographics to estimate the geographic and social network spillovers created by regional policies across the United States. Our analysis shows that the contact patterns of people in a given region are significantly influenced by the policies and behaviors of people in other, sometimes distant, regions. When just one-third of a state’s social and geographic peer states adopt shelter-in-place policies, it creates a reduction in mobility equal to the state’s own policy decisions. These spillovers are mediated by peer travel and distancing behaviors in those states. A simple analytical model calibrated with our empirical estimates demonstrated that the “loss from anarchy” in uncoordinated state policies is increasing in the number of noncooperating states and the size of social and geographic spillovers. These results suggest a substantial cost of uncoordinated government responses to COVID-19 when people, ideas, and media move across borders.

Despite the availability of multiple safe vaccines, vaccine hesitancy may present a challenge to successful control of the COVID-19 pandemic. As with many human behaviors, people's vaccine acceptance may be affected by their beliefs about whether others will accept a vaccine (i.e., descriptive norms). However, information about these descriptive norms may have different effects depending on people's baseline beliefs and the relative importance of conformity, social learning, and free-riding. Here, using a large, pre-registered, randomized experiment (N=305,694) embedded in an international survey, we show that accurate information about descriptive norms can substantially increase intentions to accept a vaccine for COVID-19. These positive effects (e.g., reducing by 5% the fraction of people who are "unsure" or more negative about accepting a vaccine) are largely consistent across the 23 included countries, but are concentrated among people who were otherwise uncertain about accepting a vaccine. Providing this normative information in vaccine communications partially corrects individuals' apparent underestimation of how many other people will accept a vaccine. These results suggest that public health communications should present information about the widespread and growing intentions to accept COVID-19 vaccines.

Policy and communication responses to COVID-19 can benefit from better understanding of people's baseline and resulting beliefs, behaviors, and norms. We fielded a global survey on these topics. This report provides an overview of the motivation behind the survey design, outlines the survey content and its representation in the respondent-level data, and details the sampling and weighting designed to make the results representative of populations of interest.

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Despite the availability of multiple safe vaccines, vaccine hesitancy may present a challenge to successful control of the COVID-19 pandemic. As with many human behaviors, people's vaccine acceptance may be affected by their beliefs about whether others will accept a vaccine (i.e., descriptive norms). However, information about these descriptive norms may have different effects depending on people's baseline beliefs and the relative importance of conformity, social learning, and free-riding.Here, using a large, pre-registered, randomized experiment (N=305,694) embedded in an international survey, we show that accurate information about descriptive norms can substantially increase intentions to accept a vaccine for COVID-19. These positive effects (e.g., reducing by 5% the fraction of people who are "unsure" or more negative about accepting a vaccine) are largely consistent across the 23 included countries, but are concentrated among people who were otherwise uncertain about accepting a vaccine. Providing this normative information in vaccine communications partially corrects individuals' apparent underestimation of how many other people will accept a vaccine. These results suggest that public health communications should present information about the widespread and growing intentions to accept COVID-19 vaccines.