This paper investigates how social interactions, as shaped by religious denomination, are related to COVID-19 incidence and associated mortality in Western Germany. We observe that the number of infections and deaths during the early pandemic phase were much higher in predominantly Catholic counties with arguably stronger family and social ties. The relationship was confirmed at the county level through numerous robustness checks, and after controlling for a series of characteristics and county fixed effects. At the individual level, we confirmed that Catholics, relative to non-Catholics, have tighter and more frequent interactions with their family and friends. Moreover, the intensity of social interaction was able to partially explain the relationship between COVID-19 incidence and share of Catholics at the county level. Our results highlight the number of dimensions that have to be taken into account when designing and implementing mitigation measures in the early stages of disease outbreaks.