More than 1,000 people in North East Lincolnshire were contacted by the NHS Covid-19 app and told to isolate in the latest week, figures reveal.
The app warns people that they have been in close contact with someone who has tested positive for coronavirus.
People contacted through the app are advised to isolate for up to 10 days, although there is no legal obligation to do so.
NHS figures show 1,183 people in North East Lincolnshire were "pinged" by the Covid app in the week to July 28 – the latest available data.
However, that was a decrease from the 2,067 alerts sent out the week before.
Across England and Wales, nearly 396,000 alerts were sent to Covid app users in the latest seven-day period – down 43% on the previous week.
There has also been a significant drop in the number of check-ins to venues using the app.
There were 2.4 million check-ins in the week to July 28 in England and Wales – 65% fewer than in the previous seven days.
In North East Lincolnshire, there were 5,353 venue check-ins in the latest week, 68% fewer than the week before.
The app is being updated so fewer contacts will be instructed to isolate, after the lifting of lockdown restrictions led to a huge increase in the number of people being contacted – a so-called “pingdemic”.
Health and Social Care Secretary Sajid Javid said the “logic” behind the app is being tweaked, although the sensitivity and risk threshold will remain unchanged.
Instead of checking contacts for five days before a positive test, the app will only go back two days.
“We want to reduce the disruption that self-isolation can cause for people and businesses while ensuring we’re protecting those most at risk from this virus,” Mr Javid said.
“This update to the app will help ensure that we are striking the right balance.
“It’s so important that people isolate when asked to do so in order to stop the spread of the virus and protect their communities.”
While isolation is not mandatory for people “pinged” by the Covid app in England, anyone who is contacted and told to self-isolate by the NHS Test and Trace service has a legal obligation to do so.
Separate Department for Health and Social Care figures show in North East Lincolnshire, contact tracers told 1,633 close contacts of people with coronavirus to self-isolate in the week to July 28.
That was down from 2,854 the week before.
Contact tracers ask new patients to give details for anyone they were in close contact with in the 48 hours before their symptoms started.
The figures show 1,819 people who came into close contact with someone who tested positive for Covid-19 in North East Lincolnshire were transferred to Test and Trace in the latest week.
It means 186 contacts were not reached by the service. The figures do not include those told to isolate in specific settings such as schools and prisons.
Across England, more than 185,000 cases were transferred to the contact tracing system between July 22 and 28, with 406,000 people identified as coming into close contact with someone who had tested positive.