February 11, 2002

'MMR contains the same strains of virus as those used in the single vaccines'

In cold scientific terms, the Government has a compelling case for saying that the MMR jab is safe. It was introduced in Britain in 1988 and is used in at least 30 countries, including the US and Canada. Five hundred million doses have been administered worldwide and countries that support it have seen the three diseases almost eradicated.

The South London outbreak, where vaccination levels have fallen to 73 per cent (the World Health Organisation says a level of 95 per cent is required to prevent epidemics) shows that vaccination succeeds in keeping the diseases at bay. But there are thought to be 1,000 families who believe that the vaccine has damaged their children.

The MMR jab in Britain and America is manufactured as MMR II by the pharmaceutical giant Merck. It comprises three live attenuated viruses. “Attenuated” means the vaccine contains small portions of viruses of measles (Edmonston strain), mumps (Jeryl Lynn) and rubella (RA27/3). The dangerous segments of the viruses have been removed, leaving enough biological material to tutor a child’s immune system to recognise the whole virus but not enough to cause disease. When a child encounters one of them, the immune system, primed by the jab, can recognise it and produce antibodies to kill it. The vaccine is administered in two stages: an injection at age 12 to 15 months and a booster before a child joins school.

The vaccine is not advised for those with “impaired immunity” or a history of allergy to vaccines or egg. Listed adverse reactions for those who have the vaccine include malaise, rash, fever and nausea. Those, say doctors, are nothing compared with the consequences of, say, measles, which causes the deadly brain disease encephalitis in one in 1,000 children.

What about the main voice behind concerns, Dr Andrew Wakefield, a consultant gastroenterologist? He left the Royal Free Hospital in North London by mutual agreement last year, and is now at the International Child Development Resource Centre in Florida. He published a paper in The Lancet in 1988, looking at 12 patients with bowel disorders. Nine were later diagnosed with autism; all but one had been given the MMR jab (one had caught measles). Wakefield contends that the MMR triggers a bowel disease in some children: toxins can leak from the gut into the bloodstream, which subsequently impedes brain development. Hence his call for single vaccines to be available. But Wakefield’s research papers show no clear link. For example, a research paper to appear in the April issue of the journal Molecular Pathology shows that among 91 children with developmental disorders and bowel disease, 75 had the measles virus in intestinal (gut) tissue. Of 70 healthy children, only five had the measles virus in their gut. Wakefield supplied the tissue and is listed as a co-author.

Yet the researchers did not look to see which of the children had been given MMR (Wakefield said later that most children had been given it but several had had the single measles vaccine, which implies that single vaccines may be just as risky for vulnerable children.) Neither did they seek to establish whether the measles strain found in the gut tissue of affected children matched those in the vaccine, which would be a vital piece of scientific evidence.

Professor John O’Leary, a molecular pathologist in Dublin who co-authored the paper, said: “I stand by the findings of our research, which raises many questions about whether measles virus has a role in bowel inflammation in developmental disorder. But the research did not set out to investigate the role of MMR in the development of either bowel disease or developmental disorder, and no conclusions about such a role could, or should be, drawn from our findings.”

The editors of the journal added: “The paper did not set out to investigate the role of MMR in developmental disorders or bowel disease, and no role for MMR is suggested in it.”

In the four years since Wakefield raised his concerns, not a single researcher, not even from the Royal Free, has stepped forward to back him. No one has managed to replicate his findings. A review of the data, by Professor David Elliman, of St George’s Hospital in South London, and Dr Helen Bedford, of London’s Institute of Child Health, published last year in the Archives of Disease in Childhood, concluded that “there is no good scientific evidence to support a link between MMR vaccine and autism or inflammatory bowel disease . . . there is mounting evidence that shows no link . . . the paper (by Wakefield, suggesting that MMR had not been properly tested before its introduction in 1988) contains no new information, it has many errors, and is highly selective in the studies it includes.”

Unfortunately, the debate has become so acrimonious that it has acquired the whiff of an anti-Wakefield vendetta, adding to parental fears. Many medical organisations, meanwhile, have joined the Government in insisting that MMR is safe, among them the WHO, the British Medical Association, the Royal College of General Practitioners and the Royal College of Nursing. Two independent advisory committees — the Committee on the Safety of Medicines and the Joint Committee on Vaccination and Immunisation — also endorse MMR.

Dr Thomas Vernon, vice-president of policy, public health and medical affairs in Merck’s vaccine division in Pennysylvania, says that the combined MMR vaccine contains exactly the same strains of virus as those used in the single vaccines and “the same immunological benefit” .

The Government’s main concern is “compliance”. The three separate vaccines require a course of six injections (initial vaccine plus booster). It is an immunological idiosyncrasy that where vaccines are given singly, each dose should be administered at least 30 days apart (if several vaccines are administered in the same dose, as in the MMR jab, that is considered safe). So a complete course of individual measles, mumps and rubella vaccines would require a minimum of 180 days.

The Government fears that children would be left vulnerable between jabs, that courses would not be completed, or that scared parents will reject vaccination completely. It cites the whooping cough scare of the 1970s, when the pertussis (whooping cough) vaccine was split from the DTP (diphtheria, tetanus and pertussis) vaccine.

Vaccination against whooping cough fell from 80 per cent to 30 per cent, 100,000 children developed it and 100 died. Vernon comments: “Where there are no extra risks, as in the case of the MMR jab, we agree wholeheartedly that combination vaccines should be given in preference to the single vaccines. Separate vaccines requires six different needles on six separate visits and are less painful . . . the reality is that delays in vaccinations happen, children get sick and you end up with the ultimate tragedy, which is what’s happening in South London.”

The single vaccines are not licensed for use in this country (because the triple vaccine is used overwhelmingly, there is little point). This means that doctors administering them are personally responsible for any adverse reactions (opening them to litigation if things go wrong) and must procure supplies from abroad. This explains why so few doctors are making it available. It is unlikely that the Government is refusing to make the single vaccines available for cost reasons.

Is a triple live vaccine too much for some children? It seems not. A paper in the American journal Paediatrics, based on research at the Children’s Hospital of Philadelphia, says that an infant’s immune system can theoretically cope with 10,000 live vaccines at once.