Meta-analysis and my fears of MMR vaccine

Meta-analysis and my fears of MMR vaccine

Since this blog has covered the MMR vaccine throughout the 2000s, where I would regularly post news on epidemiological studies which failed to show an association between MMR vaccine and autism, I feel I ought to point people towards the new meta-analysis performed by Taylor et al published in Vaccine. I’m in the midst of marking, so have only briefly read through it. Their key findings are found in this Reuters article:

  • There was no relationship between vaccination and autism (OR: 0.99; 95% CI: 0.92 to 1.06).
  • There was no relationship between vaccination and ASD (autism spectrum disorder) (OR: 0.91; 95% CI: 0.68 to 1.20).
  • There was no relationship between [autism/ASD] and MMR (OR: 0.84; 95% CI: 0.70 to 1.01).
  • There was no relationship between [autism/ASD] and thimerosal (OR: 1.00; 95% CI: 0.77 to 1.31).
  • There was no relationship between [autism/ASD] and mercury (Hg) (OR: 1.00; 95% CI: 0.93 to 1.07).
  • Findings of this meta-analysis suggest that vaccinations are not associated with the development of autism or autism spectrum disorder.

They didn’t find any evidence of publication bias that would have led to these results.

They also didn’t use VAERS-based studies (spontaneously reported data similar to the Yellow Card Scheme in the UK), because it creates absolute junk in this context (particularly when mined by anti-vaccine cranks or those with snake oil autism “treatments”).

The sad thing about this whole escapade is that all this work has been performed for nothing. You do epidemiology on such possible associations when you have a signal of potential harm, but there never was a signal. It was manufactured and fixed, and amplified by activists and the media. Epidemiology studies were ignored and discounted as they came out, afterall Wakefield was “listening” to patients, and the media reports of such studies paradoxically tended to draw further attention to activists and the hoax association. Arguably, the problems with Wakefield’s PCR, the failure to find support for his hypothesis in virological and biopsy studies and Brian Deer’s journalism were more important in countering the hypothesis (because the scare was based in Wakefield’s imaginative hypothesis of a mechanism, than any real signal).

There’s a nice in epilogue in this Reuters article (which is in the paper):

As an epidemiologist I believe the data that is presented in this meta-analysis. However, as a parent of three children I have some understanding of the fears associated with reactions and effects of vaccines. My first two children have had febrile seizures after routine vaccinations, one of them a serious event. These events did not stop me from vaccinating my third child, however, I did take some proactive measures to reduce the risk of similar adverse effects. I vaccinated my child in the morning so that we were aware if any early adverse reaction during the day and I also gave my child a dose of paracetamol 30 min before the vaccination was given to reduce any fever that might develop after the injection. As a parent I know my children better than anyone and I equate their seizures to the effects of the vaccination by increasing their body temperature. For parents who do notice a significant change in their child’s cognitive function and behaviour after a vaccination I encourage you to report these events immediately to your family physician and to the ‘Vaccine Adverse Event Reporting System’

The Wakefield story broke in 1998, which is when our first child was born. I remember being concerned at the time when I I first heard Wakefield’s claims on the news (A Lancet paper, and a press conference from a researcher at one of the UK’s leading hospitals). Even though I wasn’t convinced, as someone working in a drug safety unit at the time, at the back of your mind the fear does sit there. I remember worrying that I might be wrong when taking her for the vaccine. Discussions with other parents at the time highlighted fears.

If only the media, Wakefield, the Lancet, and the activists had thought about what might happen if they were wrong.

Photo from Suw Charman-Anderson.