Table 3.

Key lessons learned from this review along with suggestions

	Lessons learned	Suggestions/research gaps
Effectiveness	Digital contact tracing can control COVID-19 if the population uptake surpasses 90%.	As a 90% uptake is difficult to be achieved, digital contact tracing should be combined to manual contact tracing.
Digital vs. manual	There is no clear evidence that digital contact tracing can substitute manual.	Further research is needed with empirical data.
Proximity/location accuracy	Proximity/location accuracy highly varies on the technology used and the indoor or outdoor setting	To avoid false alerts or exposure notifications, the choice of proximity awareness technology should be central when designing a digital contact tracing system.
Proximity awareness technology	BLE is preferred.	As proximity accuracy is low with BLE, alternative technologies such as UWB should be promoted.
Architecture	Decentralized architecture allows for higher personal data privacy	Architecture should ensure the highest data privacy standards.
Privacy	Most studies raise privacy and ethical concerns related to personal data.	The need for epidemiological information should not lead to personal data privacy infringement. Governments should build a legal framework ensuring personal data privacy to gain people’s trust.