This paper presents a mobility indicator derived from anonymised aggregated mobile positioning data. Even though the indicator does not provide information about the behaviour of individuals, it captures valuable insights into the mobility patterns of the population in the European Union (EU) and it is expected to inform responses against the coronavirus disease 2019 (COVID-19) pandemic.
Spatio-temporal harmonisation is carried out so that the indicator can provide mobility estimates comparable across European countries. As an application, the indicator is used to study the impact of COVID-19 confinement measure on mobility in Europe. It is found that a large proportion of the mobility patterns can be explained by these measures. The paper also presents a comparative analysis between mobility and the infection reproduction number Rt over time.