Running the risk: Immunity and mobility in response to a pandemic

The relative effectiveness of non-pharmaceutical interventions, such as lockdowns and work-from-home mandates, depends on whether individuals adjust their social behavior in response to infection risk when policy restrictions are absent. Exploiting geographic variation in COVID-19 exposure during the first wave, three key results emerge. First, we find evidence that areas with relatively high excess death rates during the first wave of the pandemic had relatively low excess death rates during the second wave. Second, using granular mobility data from GPS devices, we show that the same areas saw relatively high mobility during the second wave, which may suggest that the first finding is driven by an immunity effect. Finally, the heterogeneity analysis reveals that scarring, behavioral responses, and immunization may operate with varying intensity across municipalities with different age compositions, yielding observable differences in both second-wave mobility and mortality patterns.