Visitors to the UK will be asked to download the NHS coronavirus contact-tracing app.
Contact details will also be requested “so that we know where people are”, Transport Secretary Grant Shapps said at the Downing Street press conference.
The app is being trialled on the Isle of Wight, where more than half of residents have now downloaded it, Mr Shapps added.
“The actual number is 72,300,” he said.
Reaching such a number is crucial. Earlier this month, Mr Shapps said that about 50% to 60% of people needed to use the software for it to be effective.
A national rollout of the application – developed by the health service’s technology arm, NHSX – is expected later this month.
It is part of a test, track and trace strategy considered central to efforts to slow the spread of COVID-19.
It works by using Bluetooth to detect when your phone has been near a handset belonging to someone reporting coronavirus symptoms.
The user is then sent a notification, offering advice on how to stop the disease spreading.
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A COVID-19 swab test can be ordered via the app for those who have symptoms, the government has said.
It is available on Apple IOS version 11 and higher, and Android version 8 and upwards.
The prime minister’s official spokesman has admitted the “pilot has uncovered some issues” which are “being fixed as we go along”.
He added: “The view of the health secretary and those working on the app is that it is progressing well.”