Japan’s COVID-19 contact-tracing app has been downloaded more than 4 million times since its launch a week ago as the government seeks to head off a second wave of infections now that businesses and schools have reopened.
Yuki Furuse, a professor at Kyoto University, said there’s debate about whether usage has to be that high to be effective, but “the more people use the app, the more it would be effective for the outbreak response.”
The app, named COCOA for Contact-Confirming Application, was designed by Microsoft and is available for Apple’s iPhone and devices using Google’s Android software. It uses Bluetooth signals to detect contact with nearby users lasting 15 minutes or more. If a user later tests positive for the virus, their contacts can be traced and notified through the programme.