According to Test and Trace data, in the week to July 28, there were 156 new Covid-19 cases reported in those in their 20s.
There were 132 new cases in those aged between 10 and 19 and a further 107 in people in their 30s.
A total of 34 cases were reported among all over 60s.
All of these age groups have seen a fall in the number of cases reported - in the week to July 21 there were 174 cases in those in their 20s; 185 in those aged between 10 and 19; 180 in those in their 30s and 38 in all over 60s - but the difference between the figures for young and old is still pronounced.
The highest rate is in the 20 to 24 age group at 874.2 per 100,000 people as of July 30. The week before, on July 24, the rate for this age group was 648.3.
These figures come as North West Anglia NHS Foundation Trust (NWAFT), which runs Peterborough City and Hinchingbrooke hospitals, announced three further Covid-19 deaths since July 20.
Caroline Walker, chief executive for NWAFT, said: “I can confirm that sadly 703 patients being cared for in our Trust have passed away since we began reporting Covid-19-related deaths.
“There have been 227 at Hinchingbrooke Hospital and 477 at Peterborough City Hospital.
“All patients were aged 30 to 98 years old and the majority of those had pre-existing health conditions.
“Our thoughts and condolences remain with the patients' families and loved ones at this difficult time."
Meanwhile, data from the NHS Covid-19 app shows that the number of people 'pinged' and told to self-isolate has dropped for the first time in nine weeks, since the end of May.
In the week to July 28, a total of 1,454 people were alerted via the app to potential contact with someone who has tested positive for Covid-19.
This is a fall of more than 500 people compared to the week prior.
The #dotherightthing campaign, aimed at bringing Peterborough's vaccination levels in line with the rest of the country in order to protect residents, has been backed by the mayor of the combined authority.
Mayor Dr Nik Johnson said: “Having the local community and workplaces vaccinated is vital to keep the numbers of Covid-19 hospitalisations and deaths as low as possible. There is also emerging evidence that the vaccine can also help stop the virus spreading.
“As the country cautiously moves out of restrictions, we need to be more considerate of each other, which includes getting the vaccine to not only protect ourselves but also to protect our colleagues and our communities.
“Please get your first and second jabs to help keep communities safe and to keep Cambridgeshire and Peterborough working.”
Councillor Wayne Fitzgerald, leader of Peterborough City Council, added: “Without doubt the best thing you can do to protect yourself from Covid is to get fully vaccinated. This means having two jabs at the right time.
“This really is road out of this pandemic. If we all have the vaccine it will mean we are winning the battle against this horrible virus.
“Make sure you are doing the right thing and get your first and second jabs.”