The number of people who have tested positive for Covid-19 has fallen in England by 15% week on week, the first drop since the start of December.
Some 330,871 people tested positive at least once in England between January 7 and January 13, down from 388,037.
The statistics from Test and Trace may fuel hopes that the third national lockdown that began on January 6 has helped with a levelling off cases.
But the figures contrast with latest REACT survey by Imperial College London, which found the number of people infected between January 6 and 15 was up by 50% on early December.
While Test and Trace only tests members of the public who have symptoms, the REACT survey samples people who are also asymptomatic and its backers say it gives a better estimate of the prevalence of the virus.
In the latest weekly statistics, turnaround times for tests also improved week on week, with 53.7% of “in person” tests – regional site, local site or mobile testing unit – up from 31.5% on the previous week.
Test and Trace successfully reached 86.7% of the people who received a positive test result, and 92.9% of their contacts.
Of the 351,567 people transferred to the Test and Trace system in the week to January 13, 86.7% were reached and asked to provide details of recent close contacts.
This is down slightly from 87.7% in the previous week.
Some 12.1% of people transferred to Test and Trace in the week to January 13 were not reached while a further 1.2% did not provide any communication details.
Despite the drop in positive cases reported by Test and Trace, the debate over the effectiveness of the third national lockdown was reignited by the new REACT study data.
Its report said there are “worrying suggestions of a recent uptick in infections”. Steven Riley, professor of infectious disease dynamics at Imperial College London, told TimesRadio “were the lockdown working effectively, we would certainly have hoped to have seen a decline.”
Health minister Lord Bethell said: “Around one in three people with Covid-19 don’t display symptoms, meaning you can infect others unknowingly.
“It is therefore crucial that we continue to follow public health guidance, and all play our part by following the rules and reducing our social contact to slow the spread of the virus.”
Test and Trace chief Dido Harding hailed the progress on turnaround times. She said: “The pace of our response has been set by the virus and I would like to thank everyone who has worked so hard to ensure NHS Test and Trace is meeting this challenge. It has been a strong start to the year.”