Dozens fewer people in South Holland were contacted by the NHS Covid-19 app in the latest week, following a change aimed at cutting isolation alerts.
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.
And from Monday (August 16), those fully vaccinated against Covid-19 will no longer have to self-isolate if they have been in close contact with someone who tested positive for the virus.
NHS figures show 381 people in South Holland were "pinged" by the Covid app in the week to August 4 – the latest available data.
That was a decrease from the 412 alerts sent out the week before.
The app has been updated meaning fewer contacts are now being 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”.
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 – although from August 16 this will only apply to those who haven’t had both jabs.
Separate Department for Health and Social Care figures, which cover larger council areas, show contact tracers told 4,544 people in Lincolnshire to self-isolate after being in contact with someone who tested positive for Covid-19 in the week to August 4.
That was up from 3,874 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 5,108 people who came into close contact with someone who tested positive for Covid-19 in Lincolnshire were transferred to Test and Trace in the latest week.
It means 564 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, nearly 162,000 cases were transferred to the contact tracing system between July 28 and August 4, with 139,000 people identified as coming into close contact with someone who had tested positive.
NHS figures show the number of people testing positive for Covid-19 has been falling for the last two weeks.
According to separate data from the Zoe Covid Study, a not-for-profit initiative supporting Covid-19 research, there are currently 45,900 new daily symptomatic cases of the virus in the UK on average, based on PCR and lateral flow test data from up to five days ago.
While this is a fall from the 46,900 average daily cases reported last week, researchers said the small decrease is small suggests the rate of decline has slowed.
Professor Tim Spector, lead scientist on the study and professor of genetic epidemiology at King’s College London, said: “While it’s reassuring to see loosened restrictions haven’t caused cases to skyrocket, it’s more difficult to predict the future.
"Cases remain relatively low in the fully vaccinated group, which is a sign that vaccines are working and keeping the spread at bay.”