When Omicron knocks at door: An inverted U-shape relationship between virus proximity and prosocial behavior.

The literature suggests inconsistent evidence regarding the influence of danger on prosocial behavior. We explore this issue through a nationwide survey of 8567 households in China during the COVID-19 Omicron variant outbreak in 2022. In a zero-COVID policy, China chose to quarantine all neighborhoods with viral infections. The almost random presence of infected cases provides an opportunity to examine the relationship between the proximity of danger (i.e. potential Omicron infection) and the prosocial behavior of residents in quarantine zones. For the first time, we find an inverted U-shape relationship: residents exhibit a stronger prosocial behavior when living closer to infected cases in the neighborhood, but this positive effect diminishes when they are too close to each other. Furthermore, such non-linear relationship is salient in residents' interpersonal helping but not in their cooperative behavior. Policymakers should be mindful of the different prosocial responses and target their efforts to help communities navigate quarantine periods more effectively.