Dependence analysis of social contact behaviors under the impacts of COVID-19 based on a copula approach

The spread of the SARS-CoV-2 virus during the COVID-19 pandemic was intricately linked with contact between people, but many of the policies designed to encourage safe contact behaviors were unsuccessful. One reason was that the determinants of social contact decisions have not been thoroughly investigated using scientifically sound methodologies. To fill this gap, a unique survey was designed which sought data on social contact behaviors and their determinants. Second, a copula-based behavior model was developed to jointly represent the choices of contact modes (including direct and indirect contact) and the number of contacted persons. The survey was conducted in six countries from March to May 2021 and collected valid responses from >7000 people. A comparison of five key copula functions found that the Frank function outperformed the others. The results of a Frank-based model showed that indirect contacts were significantly and positively associated with the number of contacted persons. Then the influence of various determinants, including activity attributes (e.g., frequency and travel distance), protective measures, safety level of activity settings, and psychological factors related to activity participation and risk perception, were extensively analyzed. In particular, the various heterogeneous influences in different social contact settings were examined. The findings provide scientific evidence for policymakers to promote safe social distancing, even for the post-pandemic era.