A total of 1,957 contact tracing alerts were sent to Peterborough residents via the NHS Covid-19 app in the seven days to July 21.
This is almost 500 more than the week prior, when 1,492 alerts were sent.
In addition, 120 people used the app to report symptoms of Covid-19 in the week to July 21, up from 75 the week before.
Venue check-ins also continued to fall, with 25,949 people scanning a QR code upon arriving at a venue; almost 10,500 less than the week to July 14.
According to Test and Trace data, in the week to July 21 there were 715 positive Covid-19 tests returned in Peterborough from 8,136 total tests taken. This is a 9% positivity rate.
The age group with the most cases is those between 10 and 19, with 185 new cases - 24% of those who got tested.
Among people in their 20s, 174 of 1,281 (14%) tested were diagnosed positive, up from 93 the week before.
The week to July 21 was the first week since the end of March that cases were recorded in people in their 80s. Seven Peterborough residents in this age group tested positive.
Data shows that case numbers rose in every age group in the week to July 21, except in those aged over 90 - no cases have been recorded in this age group since February.
In the week to July 14, the positivity rate in Peterborough was 6%, with 424 new Covid cases recorded.
Across England and Wales, the number of people being told to self-isolate has reached another record high, with almost 700,000 alerts sent to Covid app users.
Boris Johnson is facing growing calls to immediately allow fully vaccinated contacts of coronavirus cases to be freed from isolation if they test negative in order to prevent staffing crises.
London mayor Sadiq Khan has added to demands from businesses to end the “pingdemic” by loosening the rules for people alerted by the NHS Covid-19 app.
Mr Johnson has planned a wider relaxation of the quarantine rules to end isolation for the double-jabbed and under-18s from August 16 if they prove to be negative for coronavirus.
But there is some cross party-support for a swifter change, with Conservative former health secretary Jeremy Hunt having warned the government it faces “losing social consent” for isolation if it does not act now.