Britain said 4,973 people who tested positive for coronavirus were referred to the English test and trace system in the week to August 5, 7% up on the previous week, of whom 80% were reached and asked to provide contacts.
It said 20,638 contacts were identified and of these 74.2% were reached and asked to self isolate.
The data was released as the service said it was starting trials of a new version of its delayed mobile phone app.
(Reporting by Paul Sandle; editing by Kate Holton)
