Introducing the Harding-Hancock Efficiency test

We are going to hear a lot about Test, Trace and Isolate (TTI) in coming weeks, as we approach autumn and fears of a second wave of Covid-19 grow. Now we have moved away from national lockdown but do not yet have a vaccine, the test-and-trace system is our main bulwark against a resurgence of the disease.

But how good a defence is it? A study published in the Lancet Child and Adolescent Health this week suggests there is a huge amount at stake. Academics attempted to model what would happen in various scenarios over the coming winter, assuming schools return either full-time or on a part-time rota basis — and came to the stark conclusion that, depending on how well the tracing scheme operates, we could end up with no second wave at all, or with a second wave that would be more than twice as large as the first outbreak in the UK.