The charity said that the government should publish the results of recent trials of the app before its anticipated launch tomorrow, and claimed doing so would boost confidence among the public and encourage downloads.

The latest version of the app has been trialled in the London borough of Newham and on the Isle of Wight over the past month, but attempts to build a contact tracing app for Covid-19 have been dogged with controversy after a previous ‘centralised’ contact tracing app was dropped by the government.

The centralised version of the app used Bluetooth signal technology, and sent data on who may potentially have Covid-19 to a central computer server. It was abandoned earlier this year after a trial on the Isle of Wight.

The new version of the app is based on a ‘decentralised’ approach and uses technology designed by Apple and Google.

The Health Foundation said that the results of the Newham and Isle of Wight trials should be published to ensure that the app was both effective and would not exacerbate existing health inequalities, which risked leaving some people at greater risk of Covid-19 than others.

It said that previous concerns over a negative impact of a ‘digital divide’ leaving some people less well-protected need to be addressed, and that Newham was the first trial of the app in an area with high population density and ethnic diversity.

Polling of 2,246 UK adults by the charity and Ipsos Mori between 17th and 29th July found that participants from black and minority ethnic backgrounds, women, the youngest and oldest age groups, routine and skilled manual workers, and the unemployed had lower awareness of government plans to use a contact tracing app.

Josh Keith, senior fellow at the Health Foundation, said: “With a virus that is transmitted as quickly as Covid-19, the automated contact tracing that the app promises could prove invaluable in reducing its spread.

“However, for any major, nation-wide public health intervention it is important the government publishes evidence that it is effective and ready for mass rollout in advance of its launch. This is key for building confidence in the app as people will want to know that it will benefit them and their communities.”