The new service aims to allow anyone with virus symptoms to be tested, and those who have been in close contact with someone showing positive results to be traced and told to isolate for 14 days, even if they have no symptoms.

The government has hired 25,000 dedicated staff and aims to be able to trace the contacts of 10,000 people a day, which it said could be scaled up if needed.

It has also been ramping up the country's testing capability to 200,000 tests a day, through the establishment of 50 drive-through sites, more than 100 mobile testing units and three mega laboratories.

Unveiling the new strategy at the daily Downing Street briefing, Health Secretary Matt Hancock said it meant "we can start to replace the national lockdown with individual isolation".

"This will help us restore some of the basic freedoms that matter so much to people and doing some of the things that people are yearning to do... while controlling the virus and keeping people safe," he added. 

 

Europe's highest toll

Britain has Europe's highest death toll from the pandemic, with more than 46,000 fatalities attributed to the virus by mid-May, according to official statistics.

The government, whose separate tally of deaths confirmed by a positive test now stands at 37,460, has faced sustained criticism over its handling of the crisis.

Some experts believe the government's decision to abandon a small-scale testing and tracing regime in March has hampered Britain's response to the virus.

"Other countries implemented this early and have kept doing it since the start of the pandemic but the UK abandoned it at an early stage and is now playing catch up," said Linda Bauld, public health professor at Edinburgh University.

Facing a grilling from senior lawmakers on Wednesday, Prime Minister Boris Johnson admitted the "brutal reality" was Britain did not learn the lessons of recent epidemics.

"We didn't have a test operation ready to go on the scale that we needed," he said.

Under pressure to chart a path out of the lockdown instituted on March 23, Johnson vowed last week to have the 25,000 virus tracing staff recruited by the end of May.

He said at the time that the UK system would be "world-beating".

On Wednesday, he cautioned the scheme would need time to improve.

"It will be getting steadily better to become a truly world-beating test and trace operation in the course of the next days as we go through June," he added.

 

App delayed 

The service was originally planned to operate alongside a smartphone tracing app developed by the National Health Service (NHS), but that is still undergoing testing.

The app is now due to be launched "in the coming weeks", the health ministry said, following a "successful" rollout on the Isle of Wight off the southern English coast in recent weeks.

Until then, tracers contacting people will ask them to share information about their recent interactions to identify those they have been in close contact with.

New guidance means those who have been in close contact with someone who tests positive must isolate for 14 days, even if they have no symptoms, to avoid unknowingly spreading the virus.

While the system will go live in England on Thursday, the devolved administrations in Scotland, Wales and Northern Ireland are adopting their own approaches.

Belfast has already rolled out a tracing scheme, Edinburgh has announced its version will begin Thursday while local leaders in Cardiff are due to unveil their service early next month.

Johnson eased some aspects of the social distancing regime in England earlier this month, but leaders in the other UK nations opted to keep the stringent stay-at-home rules in place.