The weekly number of coronavirus cases in England in late August was the highest since the end of May, according to government figures.
A total of 6,732 new cases were confirmed between 20 August and 26 August – an increase of 6% on the previous week, NHS Test and Trace data showed.
But comparisons between recent and past cases should be made with caution.
The number of confirmed cases is heavily dependent on how many people are tested.
This has changed significantly since the start of the pandemic, with the number of tests processed each day increasing substantially.
Community testing has also expanded, whereas previously access was limited to symptomatic patients and key workers.
The latest figures from the Office for National Statistics (ONS) show that new infections in the community in England are continuing to level off.
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Between 14 and 20 August, an estimated 28,200 people in private households had COVID-19 – the equivalent of around 0.05% of the population.
Earlier on Thursday morning, Health Secretary Matt Hancock said the UK is finding a "higher and higher proportion" of people who have coronavirus.
He told Sky's Kay Burley that there are "operational challenges from time to time, but the testing system works well".
Some 69.4% of close contacts of people who tested positive for coronavirus were reached through Test and Trace in the week ending 26 August, down from 77.1% in the previous week and the lowest weekly percentage since the system's launch.
For cases handled by local health protection teams, 97.3% of contacts were reached and asked to self-isolate in the same period.
In comparison, 59.8% of contacts were reached in cases handled either online or by call centres.
A total of 73,081 people who tested positive for COVID-19 in England have had their cases transferred to the system since its launch in May.
Of this total, 57,368 (78.5%) were reached and asked to provide details of their recent contacts.
Some 13,958 were not reached, while a further 1,755 people could not be tracked down because their contact details had not been provided.
The government is hoping to improve the speed of its testing by pledging a £500m funding package to support trials of a 20-minute COVID-19 test.
Mr Hancock told Sky News he wants the UK to "go further" to expand mass testing using new technologies.
The figures are not as worrying as we think – but they only give us half the picture
Analysis by Rowland Manthorpe, technology correspondent
On the face of it, the new numbers about positive tests in England look bad.
Is this the start of the dreaded second wave?
As ever with COVID-19, it is hard to give a clear answer. Although it is never good when numbers of positive cases go up, there are some big caveats.
Firstly, testing has massively increased since the start of pandemic, making it hard to compare these figures across time.
In March and April, testing was largely done in hospitals so only the worst cases were caught.
Now we are finding more milder or asymptomatic cases.
The situation has not got worse – we simply have a greater awareness of the size of the problem.
The second reason to treat a rise in cases with caution is that, so far, it has not translated into hospitalisations and deaths.
There are several theories why this might be the case, but the most popular is that the virus isRead More – Source