Baroness Dido Harding told two MPs’ committees that the NHS Test and Trace programme (which she chairs) significantly reduced the spread of Covid-19 last October.

She claimed that research by the Department for Health and Social Care showed that Test and Trace was reducing the R rate (or the rate at which the virus spreads) by between 0.3 and 0.6 (a drop of between 18 and 33%).

The analysis did show this estimated effect in the R number, but this was not an estimate of the specific effect of Test and Trace. It was of its combined effect along with people with symptoms self-isolating.

The analysis estimated that the specific effect on R of the contact tracing element of Test and Trace was small, at about a 1.7-4.6% reduction.

People with Covid symptoms have been required to self-isolate since March 2020, two months before Test and Trace was launched. So Ms Harding’s quoted reduction in the infection rate comes from the combined effect of testing (which Test and Trace provides) and self-isolation with symptoms (which it may influence, but is not solely responsible for).

In short, it is hard to say how much of the effect was caused by the Test and Trace programme, and how much would have happened without it.

Baroness Harding did not include this point in her evidence. However, she did make it in a subsequent letter. 

Widely shared social media posts are comparing the cost of the NHS Test and Trace programme with the cost of constructing the Channel Tunnel. The post claims the former cost £22 billion in “just a few months,” while the latter cost £16 billion “in today’s money” over the course of five years.

While £22 billion is the allocated budget for the first year of NHS Test and Trace in England, official figures show that by October only £4 billion had been spent. Although we do not yet know how much has been spent since, or how much is likely to be spent in future, we do know that it did not spend £22 billion in a few months - as was claimed in the posts.

As for the Channel Tunnel, there are conflicting estimates ranging between £9.5 billion and £20 billion. So what cost more? The honest answer is that we don’t know yet.

The budget for the first year of Test and Trace is higher than most estimates for the cost of the tunnel, but we don’t yet know how much of it will be spent, or how much will be spent in future years. It is therefore not correct to suggest that NHS Test and Trace has already spent more than the cost of building the Channel Tunnel.

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