https://techcrunch.com/2020/05/07/nso-group-fleming-contact-tracing/

As countries work to reopen after weeks of lockdown, contact-tracing apps help to understand the spread of the deadly coronavirus strain, COVID-19.

While most governments lean toward privacy-focused apps that use Bluetooth signals to create an anonymous profile of a person’s whereabouts, others, like Israel, use location and cell phone data to track the spread of the virus.