So is the vaccine against measles, mumps and rubella safe? Yes, says the Government, now backed by one of the scientists who first raised fears. No, say campaigners who link MMR with autism. Meanwhile, parents are more bewildered than ever. Paul Vallely evaluates the claims on both sides - and reveals the new evidence that is yet to come to court

Confused? If not, you probably haven't been paying sufficient attention to the debate on the safety of the measles, mumps and rubella vaccine. Parents who thought they knew what to believe were bewildered again last week by an announcement from one of the men who first raised public fears about a possible link between the triple jab and autism. Dr Simon Murch of the centre for paediatric gastroenterology at the Royal Free Hospital in London was, in 1998, one of a group of scientists who found a connection between bowel problems and autism.

Back then, he called for more work to be done on the MMR. But on Thursday he wrote a letter to The Lancet proclaiming - in what, to the non-scientific eye, looked like a U-turn - that the MMR was safe. "There is now unequivocal evidence," he wrote, "that MMR is not a risk factor for autism - this statement is not spin or medical conspiracy, but reflects an unprecedented volume of medical study on a worldwide basis." Epidemiological evidence was now overwhelming. Measles epidemics would be "almost certain" this winter if parents continued to boycott the triple vaccine, he warned.

Almost immediately, one of Dr Murch's co-authorscounterattacked. Dr Andrew Wakefield, who detected virus particles from the measles vaccine in the bowels of children with autism - and became the scientist who first called for the MMR to be replaced by three separate vaccines - attacked the epidemiological studies on the incidence and distribution of autism as "very flawed". They had been subject to severe criticism because they "failed to address the original hypothesis that we put forward". They had, for example, lumped all autism together "when in fact autism can be caused by many things and we may just be looking at a small part of that autistic spectrum caused by MMR".

More than that, he suggested that Dr Murch's letter may have been written in response to intimidation by the medical establishment. Such pressure had been applied to Dr Wakefield to force him out of his post at the same hospital. "I know he's under similar pressure from the hierarchy of the Royal Free. His lab is under threat. He's failed to gain due promotion. He's been strongly advised to withdraw from scientific publications that involve any mention of my name or association with the MMR." All of which was denied by Dr Murch who insisted: "I have not been leant on at all." His new view was, he said, based solely on scientific evidence.

But then came the most dramatic development. There was now proof of the danger from the MMR, said Dr Wakefield - and it had not been made public.

"Senior members of the joint committee on vaccination and immunisation, in their capacity as expert advisers to the vaccine manufacturers, have been presented with compelling evidence of a link between MMR and bowel disease in children with autism," said Dr Wakefield on Radio 4's Today programme on Friday. "The situation is a national disgrace," he added and called for a public inquiry.

So what is this new evidence? And where is it? "I'm not in a position to disclose [it] to you," he said. Murkier and murkier.

The explanation for Dr Wakefield's reticence lies in a court case. More than 1,000 families who claim that the MMR was responsible for brain damage suffered by their children are on the brink of suing the manufacturers of the vaccine. Or, rather, they were.

Dr Wakefield is one of a group of scientists, mainly in the United States, who are working for the children's lawyers in this class action. They claim to have damning new evidence, which they were keeping under wraps as sub judice until it came to court in April 2004. But last month the Government's Legal Services Commission withdrew the legal aid which was funding the action. The timing was, to say the least, odd. Some of the parents had been receiving legal aid for 10 years. The class action had been in preparation for four years. And then, just six month before the case was to come to court, the plug was pulled.

Lawyers for the parents are still reluctant to disclose the new evidence since they are applying - acting without pay - for a judicial review against the commission's decision. To fund their activities the families this weekend launched a fighting fund on their website at

What the new evidence is said to reveal is the most striking link yet between the triple jab and autism. The measles virus (shown below) has been found in the spinal fluid - and therefore the brain - in three of the six test case children at the centre of the High Court battle. By contrast the virus was found in only one of more than 20 control samples - taken mainly from spinal taps on children with leukaemia. Parents from the test case wanted to obtain the spinal fluid samples from which the newest evidence was eventually drawn. But every hospital they approached in Britain refused permission for the tests, which were deemed "invasive and unethical". So they went to the US. But when they arrived with the disabled children in Michigan the hospital there suddenly withdrew at the 11th hour. When they found a replacement clinic the defendant drug companies made an emergency application to the High Court in London for an injunction to prevent the tests. It was declined, but the parents were told to delay the samples so that the drug firms could send a doctor; they sent a lawyer instead.

The tests were eventually done. On the way home, however, the parents were forcefully quizzed by customs officials - both in the US and on their stopover in Amsterdam - who had evidently been well briefed. Small wonder that the beleaguered parents are suspicious of the authorities.

I have to declare an interest here. My son has been given separate jabs. There is Crohn's disease - the bowel disorder implicated by Dr Wakefield - in the family. So we were not prepared to take any risks. He has had the rubella and the measles inoculations. We are waiting for the supply of the mumps vaccine to arrive, though we are not anxious since the big danger from mumps is in puberty.

This highlights part of the dilemma over vaccines. They do two things; they protect the individual, and they protect the whole population. The interests of the two are not synonymous.

A small boy does not have much risk from rubella; the main reason for the jab is to control the disease generally, and protect those at risk: if a woman contracts rubella early in pregnancy, there is a 90 per cent chance her baby will suffer mental and physical defects. Measles, by contrast, is a serious threat to both individual and the population. With mumps the real risk is to a pubescent youth or man; vaccinating toddlers is mainly about creating herd immunity, not individual protection.

What is best for the child and best for the nation are not therefore completely congruent. Dr Murch's argument is that the divergent risk is so statistically small that it is as irrational for a parent to refuse the MMR as it would be to allow their child in a car or a plane.

But when parents make the risk/benefit calculation with a vaccine it is not the statistical probability which weighs with them. Instead they ask why should they take any risk with their child, especially when the Government argument against single vaccines is so weak. (It claims many parents will forget to return for the next jabs and that children are exposed to extra risk in the six-week periods between jabs.)

The problem for the Government ought to be one of balance. It is undoubtedly best for general public health to force the MMR on everyone. It is undoubtedly better from the perspective of individuals that they be allowed the choice of separate jabs. Whatever the science, no one bears the responsibility for a child's health in the same way as parents.

In a liberal democracy we should expect a balance to be struck that makes allowance for both these facts, even if the resulting compromise is not the optimum from an epidemiological point of view. When, instead, we have an attitude by the authorities that smacks of bullying and manipulation, the sense of crisis is likely to grow rather than diminish.

My child had rubella. If everyone had the triple injection, it would die out

Vicky Load, 47, from Somerset, has no doubts about the value of the MMR vaccine. Her daughter Louise, 15, had rubella and is deaf, partially sighted and has difficulty walking. She also has behavioural problems.

If everyone had the MMR, the rubella that my only child has would die out, and no one else would get it ever again. After what we have been through, I really wish that could happen. Children really do need to be protected against this horrible disease which can destroy lives. It is easy for me to say, but people should have their children vaccinated.

It was a very big shock when we discovered that Louise, our only child, had rubella when she was born. She has reasonable sight in her right eye with the help of glasses, but she has a congenital cataract on the left eye which is very dense. They say it cannot be removed and that there would be no sight there anyway. As well as her sight problems she has no hearing at all, and there are problems with her legs and her mobility.

It was dreadful and a real shock to discover that she had rubella and that she was damaged in such a way. I had no symptoms, but I think I may have been in contact with someone in the bank where I worked and that I passed it on to her. I was shocked, but you can't waste time feeling sorry for yourself. You have got to get on with it.

She is a lovely girl and we love her so very much. But I passionately believe that people should have the MMR. I think the message I would give is that everyone should be vaccinated. I know people are worried about the MMR and autism, but there are other things that people need to take into account, especially rubella. The fact is that you are at risk of rubella if you are not vaccinated. That's not a theory: it is the painful reality.

If the MMR vaccine uptake does not start to increase soon there is a real risk of outbreaks of rubella, which is extremely dangerous to unborn children. MMR has been a huge success in reducing the number of babies born deaf and blind as a result of rubella and as far as I known there is no scientific evidence of a link with autism.

Before, he was a happy boy, laughing a lot. He was never the same again

June Cox-Smith says her son Edward came home a different child after he had the MMR vaccination. He was vaccinated at the age of 13 months and she says he has never been the same since.

He is six and a half now and he is severely autistic. He cannot communicate with other people in a normal way.

His speech is very limited; he cannot talk to people, and his handwriting is limited too, although his intelligence is high. He has problems with all kinds of communication.

He has no social skills and cannot join in with other children when they are playing. He also has very little imagination, although he is very affectionate. Someone told me that being as autistic as he is is like being dropped on Mars and not knowing any of the social requirements. You watch people, but you have no idea what they are doing or why. You have no understanding of what is going on.

We have no doubt that the MMR is to blame. He had it when he was 13 months old, and he was very sick and he had a temperature straight away. He was ill for several days, almost two weeks, and he never recovered his old self. He was never the same boy again.

Before, he was a happy boy, playing with his brother, laughing a lot. He liked being with other people and joined in with games, and had good times. He was so very different afterwards. He came back after the MMR as a completely silent child who didn't smile. It wasn't until he was four and half that he said anything at all. He was silent, and I mean really silent. All we had until then were grunts.

We have two older children, and they both had the MMR with no problems, but Edward has been badly affected. If we had any more children we most certainly would not expose them to the MMR - no way. We feel so strongly that we did not let Edward have his booster. We also had difficulty in getting any real advice. We found that whenever we asked about the downside of the MMR, they would just start talking about children dying from measles. We know that the cause of Edward's severe autism is the MMR that he had, and we very much wish that he had not had it.

Interviews by Roger Dobson