Wednesday, June 03, 2009

MMR and freedom

Another quick interruption from my evolution series (look out for the last 3 posts very soon) however I felt compelled to comment on the flurry of MMR related stories and opinions being stirred up at the moment in the UK. Attention has peaked today because of an announcement from the former chairman of the BMA (British Medical Association) sir Sandy Macara that he believes that MMR jabs should be made compulsory. This announcement has provoked the usual round of indignation from people claiming it would be a restriction of their freedoms, they are perfectly entitled to their view of course but I don't think such a narrow view represents the whole story.

If I am honest, I can see both sides to this one, anything to do with children and risk (perceived or real) is tricky, but if the decision were mine I would fall with the BMA, the theme of this post is to look at why.

Looking at this from the perspective of the anti-MMR lobby we can see the following concerns,

  • Scientific claims of risk that are not believed
  • Ignorance and confusion about the actual evidence
  • A lack of concern for others that might be affected by the chosen course of action.
  • A concerted effort to transform the campaign into a freedom issue from purely a medical one.

I can completely sympathise with parents who feel that fear of the unknown in relation to their own children, I have two children and I have also felt that same fear, I still had them both vaccinated at the earliest opportunity though, why did I do that?.

I am a scientist and I tend to evaluate things using a rational, evidence based approach, I look at evidence (pro's and con's), I weigh up the odds, read papers and articles, listen to experts, gauge opinion and come to a decision; I'm not suggesting that everyone should be like me (perish the thought) but the way in which people tackle the process of deciding is often instrumental in the success of the outcome of that decision, it is a fact of history that taking a rational approach demonstrably delivers better results than anything else.

For other parents who may be thinking about this here are the questions I asked myself and a brief description of how I arrived at the conclusion I did, a successful one.

What evidence would show that MMR causes autism, does that evidence exist?

Simple logic would suggest that if MMR had any impact on autism rates then if we look at historical autism rates and compare current autism rates then we should see an increase. These numbers are available on the internet from reputable sources, and the answer is a resounding no change.

What are the odds of bad things happening to my children if they don't have the MMR?

You hear people saying "well I won't have it just to be on the safe side", this is horribly flawed thinking, you need to evaluate both sides of an argument to determine the answer, so I looked at the effects of measles, mumps and rubella, the mortality rates of those diseases and I found that the number of children that used to die or be seriously handicapped far exceeded the number of cases of problems with the MMR which was statistically irrelevant in comparison, clearly not having it is far more dangerous.

How many experts say it's a good thing vs. how many say it's a bad thing?

When I looked there was almost unanimous agreement among the doctors and scientists that MMR is safe; however there was one prominent dissenting voice, that of Dr Andrew Wakefield who claimed in 1998 that there was a link between MMR and autism, this is very unusual, things that are suspect usually have a much broader degree of dissent, Wakefield was in statistical terms what we call an "outlier" an anomaly, clearly not to be ignored, but certainly not to be believed at face value. When we see outliers in science it usually means more investigation is required and 99 times out of 100 means that the data is wrong or a mistake has been made. As it turns out Mr Wakefield was a fraud, his results were fabricated because he was embittered after his theory that measles virus caused Crohn's disease was scorned, he was actually seeking to discredit MMR.

What choices do I have and are they demonstrably better?

Were there any choices, could I immunise my kids a different (safer) way? Well, there was the option of having separate injections, again the figures showed clearly that doing it this way had no benefit over the single version whatsoever, in fact they show that doing it this way is slightly less reliable. Then there are the practicalities, why have 6 injections when you can have 2, if you have ever taken a small child to the clinic to have this done you will know how distressing it can be.

What about the sad stories of cases of autism, do they have any credence?

I would be the first to concede that sometimes greed gets the better of drug companies; there are many documented examples of exploitation and lies regarding companies that wish to make vast profits from selling medicine. Looking at the stories around this we see a familiar pattern parents claiming that their child was diagnosed with autism "around" the time that the MMR was given. What question could we ask to evaluate this evidence? clearly we need to look at the history again; does typical age of diagnosis of autism correlate with the age of administering MMR? The answer is a resounding yes, this is the precise age that autistic children are diagnosed anyway, the probability that we are looking at a coincidence is very high, the probability that there is a causal link very low.

If the worst happened would it have an adverse effect on anyone else?

This was the clincher for me, what would happen if my child caught measles, would anyone else be put in harms way because of my actions? The answer was an unequivocal yes. Any parent knows that at a nursery school older children mix with younger children, what would be the effect of my child catching measles and passing it onto a younger child (not yet old enough for the MMR); potentially catastrophic is the plan truth of it. Even today, in countries that don't use the MMR (primarily 3rd world countries in Africa and elsewhere) there are 30,000,000 cases and over 900,000 deaths (figures from the WHO), just let that sink in, nearly a million preventable deaths.

So where does this leave everyone? Clearly some people in the UK do not take a rational approach when evaluating these kinds of things, that's a choice they are free to make; however there are sometimes serious consequences. The following chart shows the number of measles cases plotted by year, it speaks for itself.

The WHO (World Health Organisation) had hoped that measles could be completely eradicated by 2010. That hope has now been dashed, as we witness a huge increase in cases of these ancient, yet entirely conquerable enemies.


Elizabeth said...

You have to get your kids immunized in the US before they are allowed to go to school. I was surprised when I moved here and it was optional.

Steve Borthwick said...

E, I'd be in favour of a similar system here.