https://techcrunch.com/2020/05/12/decrypted-contact-tracing-zoom-keybase-microsoft/

As the world looks to reopen after weeks of lockdown, governments are turning to contact tracing to understand the spread of the deadly coronavirus.

Most nations are leaning toward privacy-focused apps that use Bluetooth signals to create an anonymous profile of where a person has been and when. Some, like Israel, are bucking the trend and are using location and cell phone data to track the spread, prompting privacy concerns.