Registering the results of lateral flow tests is “a bit of a faff” and could be part of the reason why so few have been logged with Test and Trace, an academic has said.

Jon Deeks, professor of biostatistics at the University of Birmingham and lead of the Cochrane Diagnostic Covid-19 Test Reviews, said it was suspected that people do not register negative results as often as they register positive ones.

He added that he suspected compliance rates may have gone down, with some people “a bit fed up of using them”.

Last week, the National Audit Office warned that only 14% of the tests handed out were registered with Test and Trace.

The public spending watchdog found that, since mass testing was rolled out by Test and Trace in October, just 96 million of the 691 million Covid-19 tests distributed in England have been registered.

Asked whether this was because people do not know how to register or they are not actually performing the tests, Prof Deeks told Sky News: “I’m sure it’s a mixture of both, to be honest,

“We don’t have any collected data to see where these tests are – there were a lot of anecdotal reports saying that there are offices in schools which are full of them, and in other places.

“I suspect people are getting a bit fed up using them, certainly amongst people I talk to their compliance rate has gone down.

“The process of registering them… it’s meant to be done but it’s a little bit of a faff .

“And we suspect actually, people don’t always register the negatives as often as they register the positive, that actually affects the statistics we get back to say how much disease there is out there, so we’re in a bit of an unknown as to what’s happening and that’s not good public health management to not know where these tests are and why they haven’t been used.”

Prof Deeks said a lot of the use of lateral flow tests, including in schools, “isn’t based on good evidence”.

He told Sky News: “Well the lateral flow tests aren’t brilliant tests anyway – they’re best at detecting cases like we did in Liverpool where we can go out and there are high rates of positivity, and we can find some people who are positive and help them isolate, that’s really where they’ll be best used.

“We don’t actually know how well they work in children yet so all of the use of the tests in schools is based on a presumption that they work in the same way that they work in adults, but that doesn’t seem likely.

“So a lot of the testing that we’re doing isn’t based on good evidence anyway.”

He added: “We’re hearing about changes to what’s going to happen in schools, and we need to make sure that the schools are protected, that the children aren’t going to get Covid – mostly they don’t get Covid so badly, but some of them do and we’ve heard of serious cases coming from children.

“We do need to look very carefully at how well we can catch the cases early in schools and a lot of it will come back down to contact tracing.”