Spatial dynamics of SARS-Cov-2 and reduced risk of contagion: evidence from the second Italian epidemic wave^*

We highlight a negative association between the severity of the first-wave of SARS-Cov-2 and the spread of the virus during the second-wave. Analyzing data of a sample of municipalities from the Italian region of Lombardy, we find that a one standard deviation increase in excess of mortality during the first-wave is associated with a reduction of approximately 30% in the number of detected infected individuals in the initial phase of the second-wave. Our findings may reflect a behavioral response in more severely hit areas as well as a cross-protection between successive waves.