More than 600,000 people using the NHS Covid-19 app in England and Wales were sent self-isolation alerts in the week between 8 and 15 July.
Data shows 618,903 alerts were sent - a 17% rise from the previous week.
It comes as some fully vaccinated key workers will be exempt from self-isolating if they are pinged by the app.
Business secretary Kwasi Kwarteng told the BBC a “very narrow” list of jobs would be released today.
Self-isolation for all fully vaccinated people pinged by the app is due to be scrapped by 16 August, he added.
Latest government figures show there are a further 44,104 daily coronavirus cases in the UK, with 73 coronavirus-related deaths.
Prime Minister Boris Johnson warned cases could rise even more this week, as most legal restrictions have ended in England.
Alerts on the NHS Covid-19 app informs users if they have been in close contact with a positive coronavirus case. If an individual is pinged by the app, they are told to self-isolate for 10 days.
In England 607,486 alerts were sent to users in the period between 8 and 15 July, with a further 11,417 sent in Wales.
Downloads of the app continued to rise to 26,826,748 from 26,523,853 the previous week.
The BBC understands there is no way to know if the app has been deleted, but #DeleteTheApp has been trending on Twitter today.
A recent poll by YouGov suggested that one in ten users have deleted the app, having previously installed it.
Those aged between 18 and 24 were most likely to have deleted the app, after installing it, according to the data.