  With the COVID-19 pandemic, quarantines took place across the globe. In the
aim of stopping or slowing the progression of the COVID-19 contamination, many
countries have deployed a contact tracing system to notify persons that be in
contact with a COVID-positive person. The contact tracing system is implemented
in a mobile application and leverages technologies such as Bluetooth to trace
interactions between persons. This paper discusses different smart-phone
applications based on contact tracing system from privacy point of view.
