A World of Imprecision
Precise and definite information about real world objects is difficult to obtain, and, in the realm of medicine, such information is not always accessible to doctors for diagnosis and treatment. This is not so surprising as the relationship between symptom and disease is sometimes vague, and the state of a patient can be very hard to define. The explosion of medical knowledge further complicates the problem. Doctors are faced with a large amount of fuzzy and uncertain information, from which medical conclusions have to be derived and on which therapeutic actions have to be based.
The uncertainty of medical knowledge is well illustrated by the debate that rages over one of our medical “certainties” that of immunisation. Not just any immunisation, but the MMR vaccine. Since Andrew Wakefield (Lancet 1998 volume 351 page 637-41) published his landmark paper suggesting a link between the MMR vaccine and autism/inflammatory bowel disease the medical establishment has felt under threat. Various studies have been published which refute Wakefield’s findings. Very certain messages about the benefits of MMR vaccine are published by governments, doctors organisations and to a large extent, the press. Yet the fear of autism remains. Wakefield fights on to prove his point. Should we as doctors acknowledge that we are just a little uncertain about links between MMR and disease or should we continue to sell “ certainty”.
Tasks
· Look at the Wakefield article on-line (search for Wakefield in advanced search “author”)
· Read some of the press reports overleaf
· Look at the US government advice for doctors overleaf
What do you think? Can you be sure of your opinion/facts? How do you know what you think you know?
MMR Vaccine and Autism
1. Does the MMR vaccine cause autism?
CDC believes that the current scientific evidence does not support the hypothesis that MMR, or any combination of vaccines, cause the development of autism, including regressive forms of autism. A suspected link between MMR vaccine and autism has been suggested by researchers and some parents of children with autism. Often symptoms of autism are first noted by parents as their child begins to have difficulty or delays in speaking after age one. MMR vaccine is first given to children at 12 to 15 months of age. Therefore, an apparent onset of autism within a few weeks after MMR vaccination may simply be an unrelated chance occurrence.
An extensive study of the evidence was recently conducted in the United Kingdom. The British Committee on Safety of Medicines convened a "Working Party on MMR Vaccine" to conduct a systematic review of reports of autism, gastrointestinal disease, and similar disorders after receipt of MMR or measles/rubella vaccine. The National Childhood Encephalopathy Study (NCES) was examined to see if there was any link between measles vaccine and neurological events. The researchers in England found no indication that measles vaccine contributes to the development of long-term neurological damage, including educational and behavioral deficits (Miller et al 1997). A more recent epidemiological study also found no association between MMR vaccine and autism (Taylor et al. 1999). This study looked at the timing of autism in relation to MMR vaccination. It found no evidence of clustering after vaccination. Also, MMR vaccination rates in autistic children were the same as in the general population.
2. What about the study by Dr. Andrew Wakefield, of the Royal Free Hospital in the United Kingdom?
Current scientific evidence does not support the hypothesis that the MMR vaccine, or any combination of vaccines, causes the development of autism, including regressive forms of autism. This includes the research conducted by Dr. Wakefield.
The Wakefield Study
This study was conducted in 1998 and looked at whether the existence of the measles virus from the MMR vaccine could cause bowel disease and, in turn, cause autism. The authors reviewed reports of 12 children with bowel disease and regressive developmental disorders, mostly autism. In 9 of the cases, the child's parents or pediatrician speculated that the MMR vaccine had contributed to the behavioral problems of the children in the study.
This study was reviewed by an expert committee from the UK Medical Research Council (MRC). The Council concluded there is no evidence to link the MMR vaccine with autism. On April 3, 2000 the MRC issued a new report confirming its earlier conclusion; MMR has not been linked with inflammatory bowel disease in autism. A copy of this research report can be found in the appendix and is also available at the MRC web site, http://www.mrc.ac.uk
Limitations of Dr. Wakefield's Study
1. The study used too few cases to make any generalizations about the causes of autism; only 12 children were included in the study. Further, the cases were selected by researchers and may not be representative of many cases of autism.
2. There were inadequate groups of control children. As a result, it is difficult to determine whether the bowel changes were similar to changes in normal children, or to determine if the rate of vaccination in autistic children was higher than in the general population.
3. The study did not identify the time period during which the cases were identified.
4. In at least 4 of the 12 cases behavioral problems appeared before the onset of symptoms of bowel disease; that is, the effect preceded the proposed cause. It is unlikely, therefore, that bowel disease or the MMR vaccine triggered the autism.
3. Would it be safer to separate the MMR vaccine into its individual components--in other words, give children three separate shots, at different times (e.g., six months or one year apart), instead of one combined shot? Why do we have to use the combined vaccine?
There is no scientific research or data to indicate that there is any benefit to separating the MMR vaccine into its individual components. This idea is not based on any published evaluation of the effect(s) it may have on children. In fact, splitting the MMR vaccine into three separate doses may be harmful because it would expose children unnecessarily to potentially serious diseases. For instance, if rubella vaccine were delayed, 4 million children would be susceptible to rubella for an additional six to 12 months. This would potentially allow otherwise preventable cases of congenital rubella syndrome (CRS) to occur. Infection of pregnant woman with "wild" rubella virus is one of the few known causes of autism. Thus, by preventing infection of pregnant women, rubella vaccine also prevents autism.
// The panel
The Question: Dr Andrew Wakefield's claims about adverse reactions to the MMR vaccine are fuelling further controversy. Are parents right to hesitate over the triple inoculation?
Guardian
Wednesday January 24, 2001
Peter Todd
Solicitor acting for claimants in MMR litigation
My nine-month-old son, Alexander, has had diptheria tetanus and acellular pertussis, polio, HIB and meningitis C. Today, he is going for the tuberculosis vaccine too. So I am keen on vaccines! However, when my son's invitation for the MMR jab arrives shortly, he won't be going - at least not for a couple of years. I am acting in legal claims for a number of parents who believe the vaccine has seriously injured their child. After consideration, I would say that, although there is no evidence that it does cause autism, it is a serious possibility. More research is needed.
Verdict: Wait and see
Isabella Thomas
Spokeswoman for JABS, a parents' support group
The MMR vaccine manufacturer's own leaflet warns of possible "gastro-intestinal effects" and "neurological reactions", and we have parents reporting a range of vaccine-related illness, including epilepsy, encephalitis, bowel problems, regressive autism and profound deafness. Our membership is 2,000. It is very convenient for Andrew Wakefield to be portrayed as a lone voice, but there are many other scientists who back the questions he has raised. JAB's view is that it should be suspended for further testing, and that single vaccines should be reintroduced.
Verdict: Yes
Dr Helen Bedford
Senior research fellow, Institute of Child Health
The MMR vaccine has been in use since 1972 in the US and 1982 in Scandinavia. Before it was introduced in these countries, it underwent trials to make sure it was safe and effective. By 1988, when it was introduced in the UK, we had the benefit of many years of experience which confirmed that serious side-effects were uncommon. In 1998, Dr Wakefield and colleagues suggested there might be a connection between the vaccine and both autism and bowel problems. Studies were set up to look into the possibility. They have not confirmed Dr Wakefield's suggestion.
Verdict: No
Judith Barnard
Communications director, National Autistic Society
That is a question for the medical establishment which can only be answered by more research. Given the thousands of calls about MMR to the NAS each year, parents are not convinced. A number report that autism started in their children, who had been progressing well, directly after the MMR jab, but the link cannot be proved. We are committed to immunisation and protecting children against measles, mumps and rubella but cannot advise parents either way. The government should direct its £3m into that research, not advertising campaigns.
Verdict: Jury still out
Magda Taylor
Coordinator, The Informed Parent
There is much cause for doubt about the jab, from the way that it is injected and what it is made of, to the safety of combining the three inoculations. Before the vaccine was introduced, the death rate from measles had already fallen by 95%. The colossal scale of the drugs industry is enough to make some people sceptical, and the health service so quickly and absolutely dismisses public fears that it appears to be avoiding confronting serious issues. Many people are not even told about the yellow card system to report suspected reactions to vaccines.
Verdict: Yes
Dr George Kassianos
Spokesman, Royal College of General Practitioners
There is no doubt in my mind that there is no reason to doubt the safety of the MMR jab. Yesterday's summit found that Dr Wakefield's report was riddled with inaccuracies and did not prove links between the vaccine and autism or gut problems, along with all other studies around the world on the subject. The vaccine was tested sufficiently to be granted a licence, and these licences are not granted permanently. The medical control agency demands reviews at least every five years - irrespective of how many yellow cards it may have received.
Verdict: No