The UK government’s Covid contact-tracing app will finally launch in England and Wales on 24 September, the government has announced, more than four months later than initially promised. Currently being trialled in the Isle of Wight and the east London borough of Newham, the app was redeveloped entirely over the summer to adopt a framework created by Apple and Google, after an initial attempt to build an independent one failed to deliver reliable performance on iPhones. In the run-up to the delayed launch, businesses across England and Wales are being urged to print and display NHS posters to help users of the app check in and record their presence. The posters, which display a unique QR code for each business, can be scanned by the app, which then saves information that can be used to help contact tracers in the event of an outbreak. That approach will not, however free individual bars, restaurants and shops from having to maintain their own records of visitors for contact tracing purposes, a policy which has led to concern about possible privacy violations. Venues must still maintain their own register to collect the contact details of those who have not, or could not, install the app. “We need to use every tool at our disposal to control the spread of the virus including cutting-edge technology,” said the health and social care secretary, Matt Hancock, in a statement. “The launch of the app later this month across England and Wales is a defining moment and will aid our ability to contain the virus at a critical time. “QR codes provide an easy and simple way to collect contact details to support the NHS test and trace system. “Hospitality businesses can now download posters for their premises ahead of the launch of the NHS Covid-19 app. This will allow the public to seamlessly check in to venues using the app when it launches.” The QR code system has allowed the government to build a hybrid app, combining aspects of both the “centralised” approach it had initially attempted to create, and the “decentralised” approach required by Apple and Google. While the Bluetooth-based proximity tracing will not lead to any centralised database of movements, the QR code-based check-ins allow contact tracers to send out warnings about potential hotspots for the virus. Businesses can download and print the QR code posters from the government website from Friday. England and Wales are the last of the UK’s four nations to launch their contact-tracing apps. Scotland’s own app launched on Thursday – a day before it was expected – while Northern Ireland’s app was launched in July, as one of the first built around the Apple and Google system. Wales’s health minister, Vaughan Gething, said the app’s launch was “an important part of coronavirus response” and that it was sensible for the app to work across the two countries. He said: “Working on a joint England and Wales basis is the most practical option here, as we know there is a lot of movement across our shared border. It makes sense to use the same app, working in exactly the same way, regardless of which country you’re in. “The Welsh government has worked closely with the NHS app team to ensure the app is easy to use and gives people the right advice and guidance, tailored to the country they reside in. I strongly encourage people in Wales to download and use the app when it launches. “The more people who download and use the NHS Covid-19 app, the more it will help us to prevent the spread of Covid-19.” Professor Rowland Kao, an epidemiologist at the University of Edinburgh, warned that the app, while helpful, is “not a substitute for traditional contact tracing. “First, the app requires both ends of the contact trace to have the app downloaded (meaning that even high adoption rates may still miss many contacts) and second, there will be many instances where personal contact and ‘soft skills’ will be necessary to ensure that quarantine and testing requirements are well understood and followed. “Most importantly, even where tracing rates are high, COVID testing must not lag behind, either in terms of local availability of tests, or speed at which test results are received.”