The whole world, from Jacinda Ardern to Donald Trump, from Anthony Fauci to Neil Ferguson, has said no to the "herd immunity" madness - but, never fear, Iain Macwhirter (of all people) remains a devoted fan

I don't think I'm alone in having been genuinely confused by Iain Macwhirter's evolving (or perhaps 'meandering' is more accurate) position on the "herd immunity" debacle.  When I first spoke to him about it several weeks ago, there's no doubt that he at least partly misunderstood the concept.  He had listened to one of Jason Leitch's many media interviews, and had formed the false impression that only a small percentage of the population would need to be infected to generate herd immunity.  Based on that misconception, it's not hard to see why Iain found the idea so seductive - if the virus would go away for good as soon as, say, 5% or 10% of people were infected, and if it could somehow be contrived that those 5% or 10% were almost exclusively young and healthy people, then the strategy would make a great deal of sense.  The problem is, of course, that it simply doesn't work that way.  Herd immunity only comes about when the virus hits a brick wall because most of the people it attempts to infect are already immune - and that in turn requires the majority of the population to have either been vaccinated or infected.  Jason Leitch never made any secret about that - he was talking about allowing the virus to move through the entire population.  Patrick Vallance stated that at least 60% of Britons would need to be infected (and that may have been an underestimate, given that calculations of how infectious the virus is have drifted upwards since then).  

And we've already seen how the notion of limiting infections to the 'non-vulnerable' segment of the population is a pipe-dream.  It's not just that elderly and vulnerable people in care homes haven't been successfully 'shielded' - they've actually been hit by the epidemic to a disproportionate extent.  That was entirely foreseeable, given that people will always have to go in and out of care homes.  The only way to keep the virus out of a care home is to make sure there isn't much virus outside.

At some point, the penny dropped for Iain that herd immunity required an epidemic of biblical proportions, and another penny dropped that the scientific advice the UK and Scottish governments were receiving was at odds with the advice in other countries.  He said to me himself that the government found itself in a terrible quandary because its advisers were in a minority of one from an international point if view.  Surely these realisations must have given Iain pause for thought?  Nope, not a bit of it.  Today, even after all the carnage we've seen, even after the succession of U-turns from the UK administrations when the original plan proved to be completely unworkable, Iain has penned yet another column suggesting that British science will in the long run be proved right and the rest of the world will be proved wrong.

I don't know how to break the news to him, but the UK and Scottish governments' original scientific advice has already been proved wrong.  Totally, comprehensively, and catastrophically wrong.  How do we know that?  Because the advisers went on the record in February and early March about how they thought events would play out when the herd immunity plan was put into operation.  Catherine Calderwood stated that it would be business as usual at the peak of the epidemic - some people would be mildly ill, some people would be very ill, but we'd accept that and get on with our daily lives, just as we would during a bad flu season.  Jason Leitch said that even the most vulnerable people wouldn't be asked to avoid face-to-face contact completely, and indeed that their contact with family members would actually increase.  And Patrick Vallance stated that any form of lockdown in the UK was highly unlikely.  

How does all of the above tally up with where we actually are now?  Well, we're currently in nationwide lockdown, with the vulnerable told to isolate completely, and with everyone else told to stop going about their normal lives and to stay at home except when travel is absolutely essential.  Life in Britain is now practically the opposite of what it would look like if herd immunity had been viable in the way that the advisers fondly imagined.  They thought this virus was akin to a bad flu.  This is not the flu.  The number of deaths that would have to occur to achieve herd immunity prior to a vaccine becoming available would be utterly unacceptable to any reasonable person - around a quarter of a million in the UK, if the modelling is to be believed.

Iain criticises "Scottish nationalists" who think that the main problem is that Scotland has been tethered to a disastrous British policy, and points out that Nicola Sturgeon genuinely believed in the advice she was receiving, just as much as ministers in London did.  That's true.  She did.  But here's the thing: she was demonstrably wrong to believe that advice, and she should have been paying heed to the fact that the leading experts of the World Health Organization were saying something radically different.  There were, to be fair, mitigating circumstances: she was probably sitting in on briefings where the UK government's view was being presented to her baldly as "the science", and she may have only been dimly aware - perhaps totally unaware - of the different position taken by the WHO and scientific advisers in most other countries.  But that excuse no longer holds - she's seen with her own eyes that the confident predictions of the UK advisers were wrong, and like the rest of us she's now up to speed with the strategies that were adopted more successfully elsewhere in the world.  So what matters more than the mistakes she made a month ago is whether she's going to rectify those mistakes now, and there are some tentatively encouraging signs that she might.  She's started making reference in her press conferences to 'testing, tracing and isolating' as a crucial part of any lockdown exit strategy, which is exactly what the international experts have been crying out for all along.

Iain states that mass testing will only make sense when an antibody test is available.  Nope, the opposite is true - mass testing to suppress the epidemic would have to use a test that shows whether someone is currently infected, not whether they were infected at some unknown point in the past.  It's knowledge of current infections that opens the door for the all-important contact tracing.  Admittedly, people being tested would have to get their results much quicker than the UK seems to be managing at the moment - contact tracing four days after the event is not much use.  But if faster tests can't be used, contact tracing can still occur if people are diagnosed on the basis of their symptoms.

Iain makes a 'truthy' observation that epidemiologists know that 80% of the population are bound to be infected sooner or later, and nothing can stop that happening because there is no vaccine.  Nope, that's not what they say at all.  Projections of an 80% infection rate (in reality you'll see anything from 50% to 80%) are based on the assumption that governments don't intervene and that the public don't change their behaviour spontaneously.  The famous Imperial College paper went out of its way to point out that both of those assumptions were thoroughly implausible.  A new study for the French government estimates that, due to the lockdown, only around 1% to 6% of the French population have been infected so far.  If that's right, anything between another 9 and 59 waves of the epidemic, of equal severity to the one we've just seen, would be required to produce herd immunity.  If all that governments do is slow that process down sufficiently to prevent total collapse of the health care system, it would take many years and a vaccine would almost certainly be available long before herd immunity was achieved.  That being the case, ie. if everyone knows a vaccine will be the exit strategy in the real world, it's ethically indefensible to allow hundreds of thousands of people to die in pursuit of an unattainable objective.  No wonder that the French government seem to have concluded that a full-on suppression strategy, involving mass testing, contact tracing, ongoing social distancing and face-masks, is now the only game in town.  That will be the new normal until the vaccine is ready.

Iain sneers at people who criticise Nicola Sturgeon for "listening to the wrong kind of scientists", or for suggesting that the scientists she did listen to are guilty of "British exceptionalism".  But come on now.  It's not really good enough to say "any scientists will do".  If there's a dispute between the scientists employed by the government of one small country, and the world-leading scientists of the relevant international body, I'd suggest you'd need to have an outstanding reason to ignore the gold standard science of the international body.  What's Iain's reason?  Ah, here it is -

"Britain has some of the best epidemiologists in the world."

And that's it.  Perish the thought that "British exceptionalism" might have played any part in this disaster.