The NHS COVID-19 app is no longer in use and the Isle of Wight trial has now ended. This is archived information from 18 June 2020. If you still have the app, please uninstall it.
All the evidence shows that even at lower levels of use, the app can help reduce the rate of transmission - but the more people who download and use the app, the more effective it will be. We're working closely with Oxford University and The Alan Turing Institute to continue modelling effectiveness at different levels.