The number of people pinged to self isolate by the NHS Covid app has plummeted by 43% in a week.
Some 395,971 alerts were sent to users in England and Wales in the week to July 28, warning them they had been in close contact with a positive case.
This compares to a record 689,313 people pinged by the app the previous week, when England's remaining lockdown restrictions were lifted.
Numbers of check-ins at venues using the app have fallen by 65% to 2.4 million, in a sign that fewer people may be using the app.
Separate Test and Trace figures show 189,232 people tested positive for Covid-19 in England in the week to July 28 - a fall of 39% on the previous week.
It is the first week-on-week fall since the week to May 5.
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Some 13.9% of people could not be reached by Test and Trace to provide their contacts.
This is down slightly from 14.4% in the previous week, but is the second highest proportion of people not reached since October 2020.
Health Secretary Sajid Javid announced a major tweak to the sensitivity of the app to reduce the numbers of people being pinged.
The app will now checking contacts for two days before a positive test for asymptomatic people, rather than going back five days.
Ministers had refused to update the app to make it less sensitive - despite an outcry over the so-called "pingdemic".
Businesses sounded the alarm over staffing shortages and pictures emerged of empty shelves as thousands of people were forced into self-isolation.
Exemptions to the isolation rules had to be rushed out for key industries, allowing staff to return to work each day if they had a negative test.
Double-jabbed Brits will no longer have to isolate if alerted by the app from August 16 - and won't even be legally required to get tested.
Mike Tildesley, a member of the Scientific Pandemic Influenza Modelling group (Spi-M), said the app was "incredibly useful".
He told Sky News: "I know there have been some challenges in terms of particularly at the moment the so-called 'pingdemic', but in terms of being able to detect contact, it has been extremely valuable.
Dr Tildesley said there is a worry that if too many people are pinged, fewer may be willing to comply, but he added that the tweak will "hopefully guarantee higher levels of compliance".
"Obviously the challenge with that is that a lot of people are going into isolation and over the last few days the app has been made less sensitive."
Boris Johnson and Rishi Sunak were among those isolating over July 19 Freedom Day, after they both came into contact with Covid-stricken Health Secretary Sajid Javid.
