Time is running out to finalise a track and trace strategy that would avoid a potential second surge in coronavirus cases, NHS leaders have said.
The NHS Confederation warned of "severe" consequences to staff and patients if the right system was not established quickly and that lockdown measures should not be eased until a clear plan was in place.
Contact tracing identifies those who may have come into contact with an infected person, either through an app or by phone and email, so they can avoid potentially passing the disease on.
It follows the Prime Minister's pledge to introduce a "world-beating" contact tracing system in England from June.
Niall Dickson, chief executive of the confederation, which represents health and care leaders, welcomed Boris Johnson's pledge made at Prime Minister's Questions on Wednesday. But in a letter to Health Secretary Matt Hancock, Mr Dickson said without a clear strategy the UK was at greater risk of a second peak of the virus.
He said a strategy should have been in place sooner and if the right system was not instigated rapidly the ramifications for the NHS "could be severe".
Speaking on the Today programme, Mr Dickson said: "We are absolutely clear that contact tracing is the right thing to do, it is absolutely critical, it has got to be in place to prevent any notion of a second surge if the lockdown is being further released."
Source: 21 May 2020