Measles, the Media and the Dunning-Kruger Effect - Sean Derrig

In the last few weeks we have seen serious outbreaks of a potentially fatal, vaccine preventable disease in South Wales the North West and the North East and it looks like 2012’s record number of measles cases will be easily surpassed. Measles is highly infectious, complications are common and can be serious. Even deadly. According to the WHO it killed 158,000 people in 2011 but fortunately deaths are uncommon in the UK - but not unknown.

Last week yet another study was published by the CDC in the Journal of Pediatrics [sic!] showing fears of a link between vaccines and autism are unfounded – confirming yet again the conclusions of so many other studies. In the absence of any good data showing harm from immunisation why do so many people still expose their and others’ children to a preventable disease that risks significant morbidity and even death?

For example in the USA 1/3^rd of parents believe vaccines cause autism and 1 in 10 parents refuse or delay vaccinations because they think know better than CDC doctors expert in the field.

Let me state my biases up front.

I believe that sanitation and immunisation have transformed public health; more so even than antibiotics. I think you’d be hard pressed to find anyone working in microbiology, public health or infection control who would disagree with me. Yes, better nutrition, education and lots of other things also play a part in our life expectancy being ~80 and rising whereas 100 years ago the average lifespan was only 45.

Also I tend to give more weight to published data that I can review for myself so I can check for biases and fallacious arguments. Some journals are better than others and just because something has been published doesn’t necessarily make it true. That’s how science works – we publish our data so others can replicate and agree or challenge. It’s like a polite bar brawl and that’s why many of us like it.

Some studies are better than others and there is some utter nonsense published in ‘learned’ journals - take a look at this for an example; it argues that quantum theory provides a model for the effectiveness of homeopathy (water). Lots of science-y words but it’s quite simply gibberish. More examples later.

Anyway, back to the point. There were recent cases in the American National Vaccine Injury Compensation Program (aka the ‘Vaccine Court’) that compensated two individuals based on gossamer-thin evidence which is being hailed as a ‘vindication’ of Andrew Wakefield. It isn’t and I’ll dissect that argument if anyone’s interested but let’s start with the MMR / autism link and the former Dr Wakefield.

Wakefield Lied. Children Died.

Tempting though it is to get into a huge ad hominem against this man let’s stick to the facts rather than fall prey to the logical fallacies such as ad homs that regularly feature in arguments against immunisation.

The facts are:

1. Two years before the infamous February 1998 Lancet article proposing a link between the MMR vaccine and autism Wakefield’s group was paid £435,643 in fees plus £3,910 expenses by solicitor Richard Barr, then of the firm Dawbarns looking to prove a link between MMR and autism for a class action against vaccine manufacturers.
2. A year before the Lancet article Wakefield filed a patent for a single vaccine claiming a link between MMR, measles, irritable bowel syndrome and regressive behavioural diseases.
3. While the Lancet paper was quite nuanced and circumspect in its claims Wakefield fuelled a media frenzy - with the results we are seeing now.
4. He was later struck off for not revealing the conflicts of interest (1 & 2) as well as conducting unwarranted, unnecessary and unauthorised procedures on autistic children including colonoscopies and lumbar punctures.
5. On 28^th January 2010 the GMC described him as ‘dishonest’, ‘unethical’ and ‘callous’ and he was found guilty on 4 counts of dishonesty and 12 counts involving the abuse of vulnerable autistic children.

Wakefield is not the only one to blame; readers of former blog posts will have picked up on my disdain for the reporting of science in the popular meeja but if my central premise – that vaccines are hugely beneficial and Wakefield was a liar and a cheat who falsified data for personal gain – is correct why is he still viewed as a hero in some quarters and why do so many otherwise intelligent people find the whole anti-vaccine argument so persuasive?

Association, Anecdote, Advice, Advertisement

One thing that any scientist needs to do is to learn to evaluate data and not fall victim to the many logical fallacies out there that can lead us astray. For example, the Appeal to Antiquity so beloved of so many quack nostrums: “...used for thousands of years...”

Would you want a thousand year old intervention or one that has recently been rigorously scrutinised and proven to be effective? Traditional Chinese medicine is a good example – used for thousands of years resulting in a life expectancy sub-40 until Western medicine came along.

One of the most powerful logical fallacies is the fallacy of false cause. A subset of this is post hoc ergo propter hoc - or B came after A therefore B was caused by A. This is a very common fallacy but let’s stick with its relevance to autism and MMR.

Autism is often diagnosed at about the time the second MMR is given (3yrs and 4 months UK schedule). And when a diagnosis like that is given people always look for a cause. Something must be to blame. No matter how persuasive the post hoc fallacy argument might be logically, if a mother associates her child’s diagnosis with a vaccine that was administered a few weeks before no one is likely to dissuade her.

But association isn’t necessarily causation. I remember a first year stats question comparing live births in Denmark with stork distribution plus there is also proof that global warming is caused by lack of pirates.

And people always find anecdote persuasive; often more persuasive than anything ‘science’ says. But there are good reasons for anecdotal evidence (or hearsay) being excluded from criminal trials as well as science.

Apart from false cause one thing any scientist learns is that the plural of anecdote is anecdotes, not data. That’s why anecdotal ‘evidence’ is not allowed – but how many times have you seen an advertisement first using the appeal to antiquity followed by “used and trusted by millions!” – the inference being ‘so it must work’!

The popular media in the UK seem to be entirely devoid of the capacity for critical thought or evaluating evidence which fuels the above. I have ranted in other posts about that awful poo lady or Radio 4 consulting that Aggie ‘How Clean is Your House’ lady on public health and immunology. Essentially the meeja tends to be arts, not science-led and it shows in the quality and depth of science reporting.

Let’s be polite and call it a need to represent balance:

“So, studio audience, you’ve heard what Prof Three-Brains who has been studying this subject for decades has to say but now let’s talk to Sharon here who has reached completely the opposite conclusion by sitting on her sofa and speculating...”

Something else I’ve noticed while researching this topic is that an awful lot of the websites I’ve delved into seem to be selling some sort of alternative to these ‘evil’ vaccines. Funny that...

The Dunning-Kruger Effect

The Dunning-Kruger Effect is a common cognitive bias that leads people to think that their skill in a particular area greatly exceeds their competence. They not only underestimate their lack of competence, they tend to believe they are more competent than anyone else, especially an expert. DK has been – unfairly – summarised as being “too stupid to know that they're stupid” but this is a gross oversimplification. DK manifests itself in several ways. People who are genuinely expert tend to downplay their knowledge or ability and underestimate their skill in comparison with others. They often overestimate others’ ability to understand their field. “Well, it’s really very simple...”

This is counterbalanced by the non-experts who overestimate their skill – to quote Dunning and Kruger "this overestimation occurs, in part, because people who are unskilled in these domains suffer a dual burden: Not only do these people reach erroneous conclusions and make unfortunate choices, but their incompetence robs them of the metacognitive ability to realise it."

But don’t mistake DK with stupidity. Look at Linus Pauling: two Nobel Prizes and went totally off the rails regarding Vitamin C (elements of the Peter Principle here) or James Watson, co-elucidator of the structure of DNA and now a complete fruitcake.

The relevance of DK to the vaccine debate is that people who are unused to critically evaluating scientific data (rather than just reading the abstract) will be less likely to be able to discriminate between Cargo Cult Science, Tooth Fairy Science, a good scientific study and one riven with logical flaws or iffy methodology (such a sampling errors or poor blinding or the other things we look for to pick holes in others’ work!). But they will assume that if they are competent or successful in other areas they are quite capable of making these evaluations.

Perhaps this is why it appears that the middle classes supposedly are the least likely to take up MMR - but the data here is sketchy (savour the irony that I’m not adverse to anecdote if it supports my position and I can’t find the proper reference!)

People have taken against vaccines ever since Jenner suggested inoculating people with zits scraped off cows’ arses. And so much of the anti-vaccine information out there on the Interwebs looks plausible and persuasive. There are plenty of case studies (anecdotes, not data!) and opinion from all sorts of people who sound like they are well informed.

Some are easy to spot: anyone recommending that colloidal silver / Echinacea / vitamins / supplements as being more effective than vaccines etc with a link to buy them is usually a woo merchant. Or promoting the Naturalistic Fallacy. Oprah Winfrey is renowned for her love of alt-med woo and some British TV shows aren’t far behind, apparently (I can’t claim expert knowledge of this as I have to work for a living and so miss daytime TV).

But a key differentiator is the use of anecdote. Most diseases are self-limiting (you get better or die) and if getting better coincides with the ‘therapy’ people credit the therapy – this is another fallacy called confirmation bias. This is why men never put the toilet seat down, incidentally.

Apart from those who refuse to vaccinate their kids point blank there are those who pick and choose which ones or alter the schedule. The people working in public health who make these decisions are very, very bright people who are expert in their fields and the committees that come up with vaccine schedules or which ‘flu strains to put in next year’s vaccine are the cream of the crop.

I am not an expert in immunology but as a microbiologist I have a reasonable working knowledge of the subject and as it’s not far from my comfort zone / dubious expertise I can read the academic literature without fear. I don’t challenge the vaccine schedule but that’s not through blind faith or lack of research on my part – it’s because I haven’t found a single study that’s worth a light that links vaccines with any of the pervasive developmental disorders. Or much else that gives me significant pause for thought when getting my kids (aged one and five) stabbed the day a particular vaccine comes on to the schedule. As I write this my youngest is having his first MMR shot.

So, be informed. Be concerned by all means. Take an interest. But remember: smallpox – history. In the US immunisation has bought death due to vaccine-preventable illness down by 99%.

But globally 2 million people still die from the vaccine-preventable illnesses that used to kill about 25% of us that had been all but eradicated in the West. Until now.

I think in this case it probably is true that those who fail to learn from history are doomed to repeat it.

OK, rant over. While I await the flame responses let’s explode a few myths...

Vaccine Myths

‘Vaccines are neither safe nor effective’

“Vaccines are ineffective because no vaccine is 100% safe or 100% effective”. There is a grain of truth in this version of the Nirvana Fallacy. For example tetanus vaccine is >95% protective but ‘flu virus is usually about 75% protective. Plus there’s interesting stuff like genetic polymorphism which means individuals are differentially susceptible to the same bug. The immune system is mind-bogglingly complex and so are its interactions with the bugs it needs to fight off.

But the point is that given the numbers of doses of vaccines administered annually the proven side effects (as opposed to those claimed with no data to back the claims up) are vanishingly small.

It’s important to understand that it’s not binary: “I’ll allow my kids to be vaccinated if you can prove it’s 100% risk free and 100% effective” is a common binary view. Were that life were so simple. Reduced vaccination mean higher incidence of infection. This has been proven with measles here post-Wakefield, in Germany in 2006, in California and in Minnesota where a young child died from a from a completely preventable H. influenza Type B (Hib) meningitis.

I have seen claims that better hygiene has led to a decrease in disease and it’s nothing to do with vaccines. This doesn’t stand up as many diseases prevented by vaccines are airborne, and are not greatly impacted by improvements in sanitation or hygiene.

One of the better ones I saw was that we didn’t see the last case of smallpox in 1978, there has been a conspiracy to hide its existence by reclassifying it as chicken or monkey pox. You can read the original article here if you don’t believe me and it would be hilarious save that some people will take this utter rubbish seriously. Dr Schiebner clearly is neither a virologist nor an immunologist but total ignorance of the basic biology of – amongst other things - Varicella and Variola does not prevent her from pronouncing:

“The list of damage done by infant vaccines, coupled with the documented ineffectiveness to prevent any diseases, is endless. All those modern ills of our world start with vaccines in infancy, aggravated by antibiotics, painkillers and anti-pyretics.”

Where’s the data? There is none.

‘Too Many Vaccines Too Soon’

“We give our poor kids so many vaccines in such a short time that no wonder they get sick under this barrage of antigens (the active bits of the vaccines that the body reacts to and learns to recognise when the real thing turns up) we force on them.”

We are exposed to hundreds if not thousands of antigens every day. Even if we lived Howard Hughes-like in a totally clean environment I’d estimate we’d still raise at least a million different types of antibody. Assuming you raise that many by the age of 18 that’s 150 per day. The few dozen in the vaccines we give children are insignificant.

Mercury

Many vaccines used to contain a preservative called Thiomersal (Thimerosal in the USA) which is an organic compound containing mercury which rapidly dissociates into ethylmercury after injection. People who don’t understand the difference between elemental mercury, methylmercury and ethylmercury claim it’s a toxin that causes autism and all sorts of other stuff.

Even though you’ll get more of it in a tuna steak than a vaccine they took it out of pretty much all vaccines some years ago; not because of valid safety fears but because misinformation was causing a decrease in vaccine uptake. Were it a cause of autism one would have expected rates of ASD to fall in subsequent years. But they didn’t. So it’s not linked with autism.

Aluminium

When the folks who didn’t understand mercury figured that it wasn’t in vaccines anymore and autism rates hadn’t fallen they switched their attention to aluminium. It’s an adjuvant that makes some vaccines work better (so you need less antigen to get the response). It is at such a low concentration that it is not even slightly neurotoxic – the claim usually falsely ascribed to it.

There is a link between Alzheimer’s and aluminium that neurologists have been working on for over 40 years – and the current thinking is it’s definitely not the single cause of AD and ‘probably not’ an independent risk factor.

I believe in the idea of a dose-response curve – most of the time the more you put in the greater the effect. Perhaps the people who think this is toxic are all homeopaths so the less you put in the more powerful / toxic it is?

Formaldehyde

Another preservative. There is more formaldehyde in a pear than a vaccine and our bodies generate a pub double measure of formaldehyde every day as part of normal metabolism. The concentration in a vaccine is lower than that in our body tissues so injecting a vaccine would cause formaldehyde to be drawn from our tissues into the inoculation site!

Herd Immunity

If sufficient members of a community are immune to a particular disease then the chain of infection is broken. A slightly woolly concept to pin down numerically but the often-quoted figure is 95%. This is based on the fact that 5% of any population will still bark at passing cars, lick windows and point at aircraft overhead but estimates are anything from 80% upwards depending on the disease.

But there will always be some people in a population who remain susceptible: vaccines are not 100% effective, you can’t immunise the very young, plus the frail or immunosuppressed are still susceptible and some people have an egg allergy (and most vaccines are grown in hens’ eggs).

If people rely on herd immunity it’s both dangerous and selfish; there have been a number of outbreaks often in pockets of low vaccine uptake.

Antifreeze!

They put ethylene glycol in vaccines! That’s antifreeze. No. Sometimes a polyethylene glycol ether called Triton-X is used to make cell membranes permeable. It will not stop your radiator freezing and, again, miniscule amounts.