Where is it currently used?
The VP is already being used as proof for those choosing international travel and by cruise ships, domestically and globally. The app was already being used by over 10 million Brits in JUly, so its acceptance and usage by the public appears to have already happened. The incentive to get it, and therefore be able to travel or more easily get in to concerts or sporting events, has proved irresistible to many people who have set aside any concerns they may have (and implications for civil liberties) and gone ahead and activated it.
The NHS App carries lots of your personally identifiable information (like name, address, NHS number, email address and telephone number) so it is a good one to setup with Face ID or fingerprint/touch ID rather than rely on username and password. When you set it up you have to prove who you are for the app to gain permission to match you with the health record(including which vaccine you have had) held by your GP.
The critical ‘vaccine status’ is a 2D digital bar code (which refreshes every 30 seconds and expires after 28 days to be replaced by a newly generated one to prevent fraud) can be presented to organisations who need to check your status. Your vaccine details are not visible to the human eye. The QR screen can also be downloaded as a PDF to store, email or print in case your phone runs out of battery at a crucial moment. Alternatively, you can avoid the whole ‘process on mobile’ and call 119 to get an NHS ‘COVID-19 pass letter’.