In its communication on Short-term EU health preparedness for COVID-19 outbreaks (COM(2020) 318 final) the Commission calls for "targeted and localised non-medical countermeasures, informed by research and evidence" to avoid major social and economic consequences from large-scale lockdown measures. This study provides insights based on mathematical modelling of spatial transmission patterns of COVID-19. It also uses aggregated and anonymised mobility data shared by Mobile Network Operators with the European Commission for this purpose.