As the COVID-19 pandemic accelerates, understanding its dynamics will be crucial to formulating regional and national policy interventions. We develop an individual-level model for SARS-CoV2 transmission that accounts for location-dependent distributions of age, household structure, and comorbidities applied to Hubei, China and Lombardy, Italy. Using these distributions together with age-stratified contact matrices for each country, our model estimates that the epidemic in Lombardy is both more transmissible and more deadly than in Hubei, while rates of disease documentation in both locations may be lower than previously established. Evaluation of potential policies in Lombardy suggests that targeted “salutary sheltering” by 50% of a single age group may have a substantial impact when combined with the adoption of physical distancing measures by the rest of the population.
