Immunisation and autism

Children are often diagnosed between the ages of 18 months and two years. A child with autism most commonly has difficulties with communication, social interaction and behaviour. Autism affects around one in 1,000 Australians, with boys more susceptible than girls.

In 1998, researchers at the Royal Free Hospital in London indicated that autism may be linked to the measles-mumps-rubella (MMR) vaccination. The theory proposed that the measles component of the vaccination triggers a cascade of events, starting with inflammatory bowel disease (IBD) and ending in autism.

This theory has caused widespread concern in the medical community and panic among parents. However, further studies undertaken around the world have found no evidence that the MMR vaccine can cause either IBD or autism.

The Wakefield studies
Researchers at the Royal Free Hospital in London, headed by Dr Wakefield, first proposed a link between inflammatory bowel disease (IBD) and the MMR vaccine in 1993. Critics of this study argue that the sample was too small to be significant (25 children with IBD versus 22 children in the control group) and that the methodology was flawed. In 1998, a further study from the Royal Free Hospital suggested that the MMR vaccine can trigger IBD in susceptible children and damage the gut lining to the point where nutrients can’t be absorbed, which could lead to autism. Critics once again pointed out that the sample group was too selective to be significant (all of the children were specifically referred to the hospital because of digestive problems) and that the methodology was flawed. For example, the proposed association between autism and the MMR vaccination was only based on parental recall.

In 2004, 10 of the 13 authors of the original 1998 study (published in The Lancet) published a statement retracting the paper’s interpretation, stating that the data were insufficient to establish a causal link between MMR vaccine and autism. The Lancet subsequently retracted the original paper.

Other studies have failed to find a link
Parents fearing for their children may choose not to have them vaccinated. If vaccination levels fall too low, disease epidemics can flourish. These concerns have prompted researchers around the world to investigate any possible link between the MMR vaccine and autism. However, no group has been able to establish a firm link or replicate the Wakefield findings. For example, the Royal Free Hospital study found live measles viruses in the intestinal tracts of the children under investigation. Researchers in Japan duplicated the experiment using similar methodology and couldn’t find any measles viruses in the intestinal tracts of their subjects.

Findings of a recent English study
A group of English researchers (Taylor et al) recently investigated nearly 500 children with autism. Their findings, published in the British Medical Journal (16 February 2002), include:

• The MMR vaccine was introduced to England in 1988, but this was not associated with any jump in autism diagnoses.
• The age of diagnosis wasn’t linked to when or if the affected child had been immunised with the MMR vaccine.
• Autism diagnoses don’t cluster around the times of MMR vaccinations.

• Measles - around one in 15 children get pneumonia and around one in 1,000 experience inflammation of the brain (encephalitis). Of those who develop encephalitis, 10 per cent will die and 40 per cent will be permanently brain damaged.
• Mumps - around one in 200 children experience encephalitis.
• Rubella - around 90 per cent of infected foetuses will develop defects including deafness, blindness and brain damage.

• Your doctor
• Immunisation program, Department of Health Victoria Tel. 1300 882 008
• Autism Victoria Tel. (03) 9885 0533
• The Maternal and Child Health Line is available 24 hours a day Tel. 132 229.
• National Immunisation Infoline Tel. 1800 671 811

• A child with autism most commonly has difficulties with communication, social interaction and behaviour.
• Studies undertaken around the world have found no evidence that the MMR vaccine can cause either IBD or autism.
• If vaccination levels fall too low, disease epidemics can flourish.
• Spacing the vaccinations at six-monthly or yearly intervals is a dangerous suggestion, because children would be vulnerable to catching one of the diseases in the meantime.

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