On Oct 22, France relaunched its “StopCovid” tracing app and renamed it “Tous Anti-Covid” (All Against Covid), which has since seen an additional 1.2 million downloads for a total number of about 4 million.

“For the application to be efficient, about 20% of the population, or 15 to 20 million people, need to download it,” Digital Affairs Minister Cedrid O said on franceinfo radio.

He said similar apps were working well in Britain, Germany and Canada but gave no examples of successful contact tracing in France with the app.

Many in France have been reluctant to download the app over privacy concerns, despite the government’s reassurances that the data will not be used for any other purpose than stopping the pandemic.

O said the app would be a crucial tool in preventing the spread of infection once France ends a curfew imposed on two-thirds of the population in an effort to rein in contagion.

The app works with bluetooth and warns users if they have been within 1m of an infected person for at least 15 minutes.

“It does mean that you need to have your bluetooth on and that the other person is also using the app,” O said.

President Emmanuel Macron said in mid-October that the previously used app had not worked well and that users of the new one would be instructed to switch it on only when they are in close proximity with other people, like on the subway or at parties, and that it made no sense to leave it on all the time.

Prime Minister Jean Castex said last month that he had not downloaded his government’s coronavirus contact-tracing app because he does not take the metro.

On Saturday, France registered a new record of more than 45,000 coronavirus infections over a 24-hour period.