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Flu: the winter ahead

With MMR uptake plummeting further, parents will more than ever want reassurance over the vaccine's safety ­ GP Dr Michael Fitzpatrick, whose 12-year-old son is autistic, suggests answers to the most common questions

Is there a link between MMR and autism?

Because MMR is given after 12 months and the features of autism often become apparent at around 18 months, it is not surprising that, in cases where behavioural regression appears soon after vaccination, parents blame the vaccine. But exhaustive research has failed to confirm any causal relationship.

Professor Brent Taylor and colleagues studied the records of around 500 children in north London who had been diagnosed with autism. They found that, although there was a steady increase in the number of cases of autism (beginning 10 years before MMR was introduced), there was no sudden 'step up' or change in the trend after the introduction of MMR in 1988.

Subsequent studies in Britain, the USA and Scandinavia have also failed to support any causal association between MMR and autism. A survey carried out on all children born in Denmark between 1991 and 1998 found the rate of autism in children who had received MMR was the same as in those who had not received it.

How might MMR cause autism?

The four links in the proposed chain of causality connecting MMR to autism are speculative ­ none has been substantiated.

·'MMR immunisation leads to chronic measles infection (and immune dysfunction)'

Though it is well-known that MMR may cause minor adverse reactions, it has never been shown to cause measles. Nor has the combination of live (attenuated) viruses in MMR been shown to suppress the infant immune system, which has the capacity to respond to about 10,000 antigens at any one time.

·'Measles causes autistic enterocolitis'

The 1998 Lancet paper, which claimed to have identified a distinctive inflammatory bowel condition in children with autism, has been discredited. Claims that research by Dublin virologist John O'Leary has confirmed this condition have been repudiated by Professor O'Leary himself.

·'Leaky bowel allows toxic opioid peptides to enter the bloodstream'

If the bowel leaks peptides in one direction, it should also lose protein in the other, but an associated protein-losing enteropathy has never been reported. The theory also demands a breakdown in the protective role of the liver and the blood-brain barrier ­ neither has been demonstrated.

·'Opioid excess in the brain causes autism'

Apart from analogy ('the behaviour of autistic children is a bit like that of drug addicts or laboratory animals on opiates') and speculation about the possibly toxic role of 'opioid peptides' derived from certain foods, there is no firm evidence for this theory ­ and much against it.

The Medical Research Council considered this proposed causal sequence 'biologically implausible'.

Why shouldn't we have the choice of single vaccines?

Some campaigners blame the measles component of MMR for causing inflammatory bowel disease and autism. If they believe this, then why shouldn't the separate measles vaccine carry the same risks? Others believe it is giving the combination of three vaccines that causes damage to the infant immune system. But there is no evidence that this is the case and much evidence to the contrary.

Nor is there any scientific basis for any particular interval between the three separate vaccines. In 1998 Dr Wakefield suggested 12 months; some clinics give them six months or six weeks apart. If children get one injection every 12 months from their first birthdays, they will be three before they are protected.

The resulting pool of unimmunised children creates the opportunity for outbreaks of measles (and mumps and rubella). The children who are most in danger are those who cannot be given live vaccines (because their immune system is suppressed by disease or medication) ­ and babies in the first year of life.

The object of immunisation policy is not to provide a 'pick-and-mix' selection to the public but to provide a coherent programme for the prevention of infectious diseases. If the Government offered separate vaccines as an alternative to MMR it could be legitimately accused of putting political expediency before its responsibility to the health of children and to public health.

Shifting claims of the anti-MMR campaign

·'Measles or measles vaccine can cause Crohn's disease and ulcerative colitis'

First advanced in the early 1990s, this theory has been investigated ­ and rejected ­ by experts in Britain and Japan.

·'MMR causes autistic enterocolitis, a new inflammatory bowel disease that is neither

Crohn's nor UC'

The central thesis of the discredited 1998 Lancet paper has not been confirmed by any other published research.

·'MMR causes autism within a week'

In the cases reported in the Lancet paper, autistic features appeared ­ on average ­ within six days of the MMR jab (though an auto-immune process causing bowel inflammation would require several weeks). Campaigners have now abandoned claims for a temporal association between MMR and autism.

·'MMR is to blame for an epidemic of autism'

Since epidemiological studies have failed to confirm the MMR-autism link, campaigners now claim that MMR is to blame for only a small subset of autism cases, one too small to measure by epidemiological methods.

Useful websites

Michael Fitzpatrick is a GP in Hackney, east London, and author of MMR and autism: what parents need to know, London; Routledge 2004

My shock, grief, anxiety and anger

My son was diagnosed with autism in 1994 at the age of 18 months

James slipped from being an ever-smiling delightful, playful toddler into a subdued, withdrawn child that his older brother by 16 months eventually gave up trying to play with.

The months after the autism diagnosis I was in a state of shock, grief, anxiety and anger.

When the MMR controversy broke out in the wake of the Lancet papers in 1998 I felt compelled to establish whether the MMR vaccine James had been given could have contributed to his autism.

After satisfying myself that the claim of a connection was seriously flawed, I nevertheless witnessed in my own practice in Hackney, east London, how the MMR vaccine became a major dilemma for parents.

My 'key moment' in deciding to actively counterbalance the inaccuracies in the popular press came in 2002.

A mother of a boy newly diagnosed with autism came into the surgery to tell me how guilty she felt that by agreeing for him to have MMR, she had helped to render him autistic. Parents of autistic children have enough difficulties without having to shoulder an additional and utterly unwarranted burden of guilt over MMR.

In recent months we have grappled with the difficulties of finding suitable schooling for James. As a result I have become increasingly frustrated with the effect of the MMR controversy in distracting attention ­ and resources ­ away from the pressing problems of education and social provision for children with autism.

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