The NHS Test and Trace app may have prevented around 284,000 Covid infections between October and December, a study suggests. Research by the University of Oxford found between 100,000 and 900,000 cases in England and Wales were prevented by the app's exposure notifications. Experts said the results show the benefits of using contact tracing apps, particularly in countries waiting for 'full protection from vaccines'. The study said the contract tracing app sent around 1.7million exposure notifications in the last three months of 2020, as a result of 560,000 app users testing positive. It estimated around six per cent of app users that receive a close contact notification will go on to report a positive test themselves — a similar rate to manual testing.