Derivation of the effective reproduction number R for COVID-19 in relation to mobility restrictions and confinement

The spread of COVID-19 is posing an unprecedented threat to health systems worldwide[1]. The fast propagation of the disease combined with the existence of covert contagions by asymptomatic individuals make the controlling of this disease particularly challenging. The key parameter to track the progression of the epidemics is the effective reproduction number R, defined as the number of secondary infections generated by an infected individual[2]. The suppression of the epidemics is directly related to this value, and is attained when R