As part of measures to help control the spread of coronavirus, the UK government is to introduce a track and trace system.
Despite NHS leaders warning that action to control future spread is coming very late, the Prime Minister said a test, track and trace system will be in place in England by 1 June.
What is the test, track and trace system?
Contact tracing is a long and laborious process that has been likened to detective work.
It is carried out by public health officials and involves interviewing a patient to identify anyone who they have recently had close contact with.
Health officials then alert these people that they may have been exposed to a virus, and often encourage them to quarantine themselves so as to avoid any further spread.
Contacts who are considered to be particularly high risk are intensely monitored to identify any signs of infection.
Such a tracing system is used to help slow the spread of infectious diseases and has been implemented in several countries, including Hong Kong, Singapore and Germany.
When will tracing be ready in the UK?
Boris Johnson has said 25,000 contact tracers will be in place by 1 June, with the ability to track 10,000 new cases per day.
An NHS contact tracing app is also currently being trialled on the Isle of Wight, and was initially meant to be launched across England in mid-May.
In Northern Ireland, a telephone contact tracing system is already in place, and one is also being trialled by the Scottish government.
In Wales, the government wants its “test, trace, protect” programmed to be operational by the end of May.
Is it too late to implement a tracking system?
Security minister James Brokenshire said he remains “confident” a test, track and trace system will be in place in England by 1 June, but admitted the NHS app would not be ready in time.
Mr Brokenshire suggested that “technical issues” were to blame for the hold-up, after the Health Secretary said it would be rolled out across England in mid-May.
Speaking at Prime Minister’s Questions, Mr Johnson said 24,000 contact tracers had already been recruited and he has confidence a “world-beating” test, track and trace operation will be in place by 1 June - the earliest possible date for the reopening of schools and non-essential shops in England.
The news comes as the NHS Confederation warned that time is running out to finalise a track and trace strategy to avoid a second peak of coronavirus infections.
Niall Dickson, chief executive of the body which represents health and care leaders, said lockdown should not be eased any further until a clear plan is in place, but expressed concern the plan was coming too late.
He said: “I think, like everyone else, we support the government's determination to set up an effective system. Our concern is that this has been done quite late in the day, we haven't yet seen the detail.
"In particular, I think we're concerned at the role of local contact tracing and how that complements what is happening at national level.
"The directors of public health have expressed concern at not being involved until very recently.
"I think it is being done very late in the day and we really do need to get on with this.”