The Scottish Government must overcome or override Chris Whitty's obstructionism. We must at long last accept the WHO's guidance, and proceed with a contact tracing operation to suppress the epidemic.

We're in limbo. The SAGE is split and the CMO's office is not behind the Minister. It's a recipe for confusion and many further deaths. Are we trying to crush the virus or let it spread? We need to know. The SAGE members must speak out now. @richardhorton1 @devisridhar (22)

— Anthony Costello (@globalhlthtwit) April 22, 2020

If the above assessment from Professor Anthony Costello is to be believed, the Health Secretary Matt Hancock is serious about belatedly bringing the UK into line with the WHO's recommendations and with international best practice by using mass testing and contact tracing to suppress the virus, but the Chief Medical Officer and the Deputy Chief Medical Officer are perversely undermining him and instead want to persevere with the British exceptionalism that has already cost tens of thousands of lives. The broader advisory body SAGE are split on the subject - which is not a major surprise, because Professor Neil Ferguson has been regularly making sensible on-the-record comments about using contact tracing to keep the number of new cases persistently low after the lockdown is eased, while on the other extreme Graham Medley made horrific remarks to The Times a couple of weeks ago about allowing the virus to spread widely and effectively sacrificing the old to benefit the young.

So what are the likes of Medley and Chris Whitty (the Chief Medical Officer) playing at? As I've said before, in Whitty's case I'm convinced this is largely psychological. He and Patrick Vallance were the authors of the discredited 'herd immunity' strategy, and they based it on a number of highly dubious judgement calls - most of which have proved to be hopelessly wrong as the weeks have passed...

* Whitty insisted that the extraordinary success of China and South Korea in suppressing the virus by means of testing and contact tracing was an illusion, and that those countries would soon be overwhelmed by a massive second wave. There was no need to wait and see if he was right about that - he was right, and that's all there was to it, and contact tracing in the UK could therefore be abandoned.

In fact, the Chinese and South Korean success has continued in the six weeks since the UK abandoned contact tracing. South Korea recorded just eleven new cases on Tuesday - the third-lowest figure since mid-February. It's impossible to say for certain that Whitty won't still be proved right at some point in the future, but the chances of that happening have receded with every passing day.

* Whitty claimed it was futile to attempt to stop the virus from sweeping across the UK, because you only needed to "look at the map" to see that it was absolutely everywhere else in the world.

This was plainly sophistry even at the moment he said it, because the virus is not capable of crossing the English Channel on its own propulsion. If an island nation keeps its own numbers low, and prevents the importation of cases by means of border controls and appropriate quarantining arrangements, it is self-evidently possible to avoid a mass epidemic no matter what is happening elsewhere in the world. But just in case there was any doubt about that point, the success of New Zealand's elimination strategy in recent weeks has helpfully driven it home.

* Whitty repeatedly characterised the infection as "mild". He speculated implausibly that the outbreak in Wuhan had not been brought under control by the lockdown, or by testing and contact tracing, but instead by a vast, hidden epidemic of asymptomatic cases that generated herd immunity. He therefore concluded that the mortality rate was likely to be much lower than estimated by China or the WHO, and that we shouldn't regard the prospect of a mass epidemic in the UK as any more alarming than a bad flu season.

In reality, early serological studies in Europe have suggested that infection rates so far are low. If that's right, the high absolute number of deaths so far would point to a relatively high mortality rate, and a potentially biblical death toll if the virus is allowed to spread widely in the UK.

Given that the whole basis for his advice to the government between January and March now lies in tatters, it's arguable that Whitty feels that whatever is left of his professional reputation will hinge upon his apparent rearguard attempts to prevent a successful testing-and-tracing operation in the UK. Why? Because if the UK manages to suppress the virus in exactly the same way that China and South Korea have done, he knows it will prove beyond a shadow of doubt that the decision - on his advice - to abandon contact tracing in mid-March (along with the unforgivable delays in implementing social distancing measures) led directly to many thousands of needless deaths. He'll inevitably and deservedly be left carrying the can in the subsequent inquiries.

The grotesque irony is, of course, that if he succeeds in frustrating a successful contact tracing operation, he'll simply be causing even more thousands of needless and avoidable deaths. So to cover himself, he's trying to reframe the debate as one that is largely about the extent of the social distancing that should remain in place. He's tacitly arguing for a relaxation by arguing there is a "trade-off" between the harm caused by the virus and the harm caused by lockdown. The big question is whether he'd be willing to relax the measures even at the expense of the reproduction rate of the virus going back above 1 - because if he is, that would be tantamount to a reversion to the herd immunity strategy, with the likelihood of hundreds of thousands of deaths needlessly occurring over the course of a stop-go epidemic.

In truth, what he talks about as a trade-off is actually a lose/lose, because if the virus is allowed to spread widely, all of the harms caused by lockdown will be magnified rather than reduced. A second much longer and harsher lockdown will be inevitable once we lose control of the situation yet again, with all of the implications for mental health and domestic violence. And even before the second lockdown is announced, people with other health conditions will be unable to access the help they need because the NHS will be completely overwhelmed by a resurgent epidemic.

Luckily, there's a way of breaking out of that vicious circle, even if Whitty himself can't bear to entertain it. The countries that are currently moving quickest away from the harms of lockdown, while at the same time minimising the number of deaths caused by the virus itself, are the ones that were most successful in getting on top of the epidemic with strategies that prioritised contact tracing - for example Germany and New Zealand. That's undoubtedly the path that the UK must follow. It's backed by hard evidence and it's backed by the WHO. Whitty and his fellow travellers must quite simply be faced down.

The Scottish Government potentially have a decisive role to play in this, because by all accounts Boris Johnson has placed a premium throughout the crisis on maintaining a common UK front on strategy. Nicola Sturgeon originally signed off on the herd immunity strategy authored by Whitty, perhaps not realising how totally at odds it was with the gold standard international science of the WHO. We've since seen the cost in human lives, and that mistake must not be repeated. Ms Sturgeon must insist that the UK lockdown is not lifted until a credible 'test, trace and isolate' operation is in place. If the UK government 'call her bluff', she must demonstrate that she wasn't bluffing and make clear that the Scottish lockdown will remain in force even if England's own lockdown is lifted prematurely. The extra time that buys must then be used to set up a distinctively Scottish contact tracing operation.

Will she do that? There are mixed signals. Her own language has been very encouraging in recent days - she's talked of the need to "continue suppressing" the virus after lockdown is lifted, and of "keeping the virus at the lowest level possible", and specifically about "test, trace and isolate" as a key component of the post-lockdown strategy. All of that is irreconcilable with Whitty's covert herd immunity approach. But on the other hand, the Scottish Government today published a Jason Leitch video on social media which uses exactly the same "reduce the peak" graphic that Leitch was touting in the TV studios when he was openly an evangelist for herd immunity. The implication is that the purpose of lockdown is simply to spread out a huge number of infections over a longer period of time, rather than to radically reduce their number. That's herd immunity in a nutshell. The hope must be that Leitch inserted the graphic on his own private initiative and that his political masters didn't grasp the abhorrent implications of what they were signing off on.

If it's true that @MattHancock is serious about contact tracing and Chris Whitty is trying to put him off the idea, then for the love of God, Matt, face Whitty down. Whitty and Vallance led this country to catastrophe once, don't let them do it a second time.

— James Kelly (@JamesKelly) April 22, 2020

If ever there was a case to show that making bespoke choices best servs the common good it’s right now. It’s time the Scottish Government firmly abandons the UK 4 nations approach, otherwise we are doomed to be handcuffed to the worst handling of Covid-19 in the world.

— 🏴󠁧󠁢󠁳󠁣󠁴󠁿CHRISTOPHER McEleny (@SNPChris) April 22, 2020

It would be interesting to know the real reason for the attachment to the '4 Nations' approach. On the face of it, it suggests an 'internationalism ends at Dover' mindset, which is associated more with Labour. Perhaps the civil service pushed it?https://t.co/K80sbr1kWN

— James Kelly (@JamesKelly) April 22, 2020

In the UK we have taken the triple hit of terrible death toll, high economic costs, and awful social consequences bc govt allowed virus to spread at the start, then had to reverse and take harsh lockdown. A true lose-lose for everyone. And economy = lives also.

— Devi Sridhar (@devisridhar) April 22, 2020

If we mobilise our national public health + primary care teams NOW for test, trace, isolate, with support from volunteers and communities, we can suppress this virus like S Korea. (17)

— Anthony Costello (@globalhlthtwit) April 22, 2020

So look again at the Table. The advantage of speed of action is clear. Korea’s test and trace policy brought their epidemic under control within 3 weeks, with just 238 deaths. Greece imposed a national lockdown before their first death and have had only 121 deaths.(19) pic.twitter.com/BauZpmTkMr

— Anthony Costello (@globalhlthtwit) April 22, 2020

"If you're hiding up a tree from a lion, you don't come back down because you've got uncomfortable, you wait to be sure that the lion is completely gone."

MP @Dr_PhilippaW speaking to me earlier today on why easing of lockdown must be carefully done.

— Helena Humphrey (@helenachumphrey) April 22, 2020

I don't believe this. If 'every life is precious', why does this video end with basically the same 'reducing the peak' graphic that Leitch was touting during the herd immunity episode? Is this his doing or is it still Scottish Government policy? https://t.co/sIAHJF2OKw

— James Kelly (@JamesKelly) April 22, 2020

I'm trying not to cry at night with worry that she's going to cave in to Westminster and not re-institute our test and trace operation before relaxing the lockdown. Lives are at stake. This is more important than not having a confrontation with WM.

— Morag (@DrMoragKerr) April 22, 2020

Dear COBRA - We are seriously worried that the advice you are receiving is not considering evidence from non-UK scientists who have very clear messages on how to exit lockdown safely. Please would you meet with us as a matter of urgency. @globalhlthtwit @devisridhar

— richard horton (@richardhorton1) April 22, 2020