'Completely wrong': Boris Johnson's plans for mass coronavirus testing may not work, government's top scientific adviser warns

The government’s top scientific adviser has poured cold water on ministers’ ambitions to develop mass coronavirus testing programme to reach up to 4 million people within months.

Launched by the health secretary, Matt Hancock, last month, the programme – codenamed Operation Moon Shot – was talked up again by Boris Johnson today in his first Downing Street press conference since July.

But chief scientific adviser Sir Patrick Vallance said it would be “completely wrong” to assume that the rapid turn-around tests touted by the prime minister as a panacea for resolving the Covid crisis would even work.

Speaking just moments after Mr Johnson said the Moon Shot project could produce a test to tell people within 15 minutes whether they are infected, Vallance cautioned: “There are, as always with technologies, unknowns and we would be completely wrong to assume this is a slam dunk that can definitely happen.”

Leaked documents, whose contents were reported by The British Medical Journal and The Guardian, suggested the cost of the programme could soar to a massive £100bn.

And chief medical officer Chris Whitty warned that even if the tests can be produced, it could be a long time before they are available.

“My own view is that I think it is likely that we will have tests of this sort at some point in the not too distant future, but that not too distant future covers quite a wide time range,” said Prof Whitty.

He added: “We do have to be absolutely sure that these tests work and that they work at scale and that is what we’ll need to be trying to develop over the next period.”

Current capacity for antigen tests to tell whether individuals are infected with Covid-19 is around 250,000 a day, though the number of tests actually conducted routinely falls well below this level.

Mr Hancock last month said that work was being “ramped up immediately” on a saliva-based test which would be quicker and easier than the current swab to the back of the nose and throat.

The health secretary did not put a timescale on its introduction, but said he wanted to make regular population-wide testing for coronavirus “the norm”, so that people could regain freedoms lost under lockdown restrictions.

And Mr Johnson suggested that the programme could be part of the drive to allow a return to normality by Christmas.

“Through that moon shot of daily testing – everybody gets a pregnancy-style test, a rapid turn-around test in the morning, 15 minutes later you know whether you are infectious of not,” he said.

“You may not know whether you are infected or not, but you know whether you are infectious, or not, and that gives you a kind of passport, a freedom to mingle with everybody else who is similarly not infectious in a way that is currently impossible.”

Mr Johnson added: “We are aiming for that. We are driving for that. As I have said … we cannot be 100% sure that we can deliver that in its entirety.”

But asked whether the proposed mass daily saliva testing could work, Sir Patrick said: “Some of them we don’t yet know that they work. So things like lateral flow tests are not yet being used widely, they’ve not been validated.

“There are prototypes which look as though they have some effect, but they’ve got to be tested properly and so there are, as always with technologies, unknowns and we would be completely wrong to assume this is a slam dunk that can definitely happen.

“I think this needs to be tested carefully.”

Prof Whitty said “we are in a much better place” with a greater understanding of the pandemic and provide testing “across the system”.

“That’s the glass half full,” he said at the Downing Street press conference.

“The glass half empty is clearly at any point there are more things we could do if we had more testing.”

He added: “There are still constraints and that’s one of the reasons it’s important, as with very many other things in the NHS, it’s critical that those who do need to be tested and in particular people with symptoms or people who have been told to for a variety of reasons – social care working for example – get tested.

“But it is also important that people who really don’t have a clear clinical indication currently don’t (get tested) because we do still have constraints.”

He continued: “Those constraints are not just going to magically disappear, and the demand on testing has increased.”