Dr Scott McLachlan, Postdoctoral Researcher with the Risk and Information Management Research Group at Queen Mary University of London, speaks to The Telegraph about the new NHS Test and Trace programme.
Contact tracing has been used very effectively to strangle the coronavirus pandemic in countries such as Singapore and New Zealand, and it was used in the UK at the beginning of the outbreak. As cases spiralled, it was dropped, becoming impractical.
The launch of the government's 'Test and Trace' programme marks a new phase in the fightback as the lockdown begins to lift, one the World Health Organization has said is "crucial" in getting societies back to anything like normal. The system does not currently involve the contact-tracing app, relying instead on individuals and their memories.
Dr Scott McLachlan, from Queen Mary University of London, said the average person is only going to remember around 35 percent of their daily interactions, although at the moment, lockdown measures mean it would be much higher.
For contact tracing to work, he says, an app needs to be part of the solution - and the government agrees, although the app is not ready yet.
"We are trying to adapt a solution for a different disease," he said. "For example, a sexually transmitted disease - you know the three people you had sex within the last few months, it's easy to find them and trace them. With coronavirus, you can't know who you gave it to. So it's like trying to use a square in the axle of your car."
In other countries, such as Germany, some bars have reopened with forms for patrons to fill in so they can be tracked if another customer later tests positive for coronavirus.
In the UK, even if someone suffering with coronavirus did remember their contacts, they may be either unwilling or unable to pass on contact details for them - and it is not clear how exactly the UK contact tracers will then find them, although they can then contact business owners, for example airlines, to try to reach people.