Childhood Vaccines: Protection or Peril?
Parents who fear a link between childhood vaccinations and autism long have debated with physicians, public health advocates and government health agencies who cite numerous studies showing no connection. Gary L. Freed, M.D., M.P.H. — the Percy J. Murphy, M.D., and Mary C. Murphy, R.N., Professor of Pediatrics for Child Health Delivery in the Medical School and professor of health management and policy in the School of Public Health — weighs in on this heated national debate.
Q: We hear so much about autism today. Is it more common than it used to be?
A: We don’t know with certainty. There are questions about whether criteria for diagnosing autism have expanded such that more children now receive that diagnosis. There’s also a greater appreciation for what’s known as the autism spectrum of disorders, so that many autism-like conditions are looked at and classified together. In many studies of the incidence or prevalence of autism, we begin to see all of these children included in the total, which may create the impression of greater numbers of children when, in fact, we may just be calling them something different today than we called them previously.
Q: Why are some children more severely affected than others?
A: We don’t really know because we don’t know the true cause of autism. The disorders within the autism spectrum likely are not all the same thing, and they’re likely not all from the same cause. Many of these children may have similar symptoms, but the cause of their symptoms may be quite different. When we tend to lump together all the children with similar symptoms, that may create a misleading impression that there’s a common or unifying cause to those conditions.
Q: What is the status of research into associations between vaccines and the autism spectrum of disorders?
A: All credible evidence has shown absolutely no association between any vaccine and autism. There also was, for a time, concern about thimerasol, a mercury-containing preservative in vaccines. Earlier in this decade, thimerasol was taken out of all vaccines in the U.S. except for some viral influenza vaccines. However, we have not seen autism rates fall as we’d expect if in fact autism was due to this preservative. Further, thimerasol had been removed from vaccines in Europe a decade prior, yet the reported rates of autism there still increased in a fashion similar to those in the U.S.
The idea that certain vaccines have been linked to mental illness of any type has been around for several decades; all that changes is which vaccine gets blamed for those problems. In the 1970s and into the 1980s, some believed the DPT vaccine (diphtheria, pertussis, tetanus) caused mental damage or brain damage. Once those links were disproven, different theories arose. The theory most common in the 1990s was that the MMR vaccine (mumps, measles, rubella) somehow was related to autism, and this theory was started by a now-discredited physician from the United Kingdom who both fabricated results as well as did not disclose that his initial studies were funded by plaintiff attorneys designed to create a cohort of children for a class-action law suit. It also came to light that this physician was trying to develop his own measles vaccine to enter the market once he had discredited the MMR vaccine. This physician has since lost his license in the United Kingdom, and the scientific paper that was published was retracted by the journal and all of the co-authors have retracted their names from appearing on the article itself. Unfortunately, the damage was done by that initial article. Many people now are much more familiar with the allegations than they are with the subsequent discrediting of this physician and his work.
Q: What about the international community? Does a similar debate go on in other countries?
A: We actually did a study to determine why things become concerns in some countries and not in others, and it turns out that different vaccines cause alarm in some countries and not in others. For example, in France there was tremendous concern over the safety of the Hepatitis B vaccine whereas across the channel in the U.K. there was tremendous concern about the MMR vaccine and nobody really thought twice about the Hepatitis B vaccine. In Japan, there’s tremendous concern about the mumps vaccine, not about the measles vaccine. So there are different societal issues and different factors that create concern in one country, and not in another. We found that one of the issues that affects whether a country has a great safety concern over a particular vaccine is whether or not the initial safety concern was published in a scientific journal in that country and was subsequently picked up by the press in that country. We also found that certain issues or areas are of greater concern to some countries than others; for example, in France the liver is a significant focus of societal concern. As a result it made the idea of the Hepatitis B vaccine potentially causing damage more of an issue in France than in other countries. Social and cultural environment contribute to whether or not something becomes a concern in an individual country.
Even though the measles vaccine is a concern in the U.S., it’s nothing compared to the concern that it was in the U.K. In the U.K., there was more than a 30 percent drop in immunization rates for the MMR vaccine. As a result, they had epidemics of measles, and children died of measles encephalitis and measles pneumonitis in the U.K. We are very fortunate in the U.S. that the concern did not reach such a level that many parents chose to not have their children immunized, and we were fortunate not to suffer epidemics as a result, as they did in the United Kingdom. Since the epidemics, and the discrediting of the studies allegedly associating measles vaccine with autism, the rates of immunization have increased again in the U.K. The last big epidemic of measles in the U.S. happened in the late 1980s. I was a resident at the time and cared for children who died of measles encephalitis, and it was a horrible experience both for myself as a physician, but even more so for the parents of those children who watched them die.
Q: If studies are so definitive, why does the debate persist?
A: Parents are rightfully and expectedly interested in knowing why their children have this condition. These parents love and deeply care for their children. It’s human nature to want to understand why things happen. One of the reasons vaccines get blamed for autism or other conditions is that almost all children get vaccines, and almost all vaccines are given during the first four years of life. This also happens to be the time during which the natural presentation of many disorders, including autism or other degenerative neurological diseases, occurs. These conditions occur in the same incidence whether or not children get vaccines.
There are several other things in society that have increased over the last two decades just as the number of immunizations has increased. We have more cell phones. We have more plastic. We have more pollution. We have more automobiles. I don’t mean to suggest that any of these are the causes of autism, but the simple fact that there is more of something and we’re exposed to more of it doesn’t create a cause-and-effect relationship. We’ve actually done studies of immunization and found no association between the increase in immunizations or components of immunizations and the rise in the number of cases of autism diagnosed in the U.S.
Q: How does the recent case of the 9-year-old Georgia girl, Hannah Poling — in which the federal government agreed to compensation and concluded that childhood vaccines aggravated an underlying disorder and predisposed her to autism-like symptoms — affect the debate?
A: Hannah Poling had an underlying mitochondrial defect, meaning that a certain part of her cells — the engine of her cells, the mitochondria — were not normal. Children who have this condition who experience fever from any cause can have an abnormal response or an impact on their mitochondria so that they do not function normally. Hannah Poling received a vaccine that resulted in a fever. This fever caused her mitochondria, because of the underlying condition, to malfunction. This malfunction resulted in damage to Hannah that resulted in autism or autism-like condition. The vaccine likely caused fever. The vaccine did not cause Hannah Poling to have a mitochondrial defect — an exceedingly rare condition that could have been aggravated by anything that would have caused her to have fever, including contracting the disease that the vaccine was designed to prevent. Hannah Poling is a tragedy. Any child with autism or any chronic disorder is a tragedy. We need to be supportive of parents of children with these and other conditions. It’s our responsibility as physicians, and as health care workers. They deserve our support and our help, but that support and help doesn’t extend to falsely attributing an underlying condition to a vaccine.
Q: What do you advise parents?
A: It’s important for parents to be concerned for their children, and it’s every parent’s right to understand health care recommendations made for their children. They are entitled to ask questions about immunizations and any other aspect of their child’s health care, and it’s the responsibility of health care providers to give parents informed and reasoned answers. Immunizations prevent life-threatening and devastating illnesses for children. We’re fortunate to live in a time when we don’t have to worry about our children contracting diseases that our grandparents feared for their children. Certain diseases, such as diphtheria and polio, have been eradicated as a result of immunizations, and each new vaccine means more diseases that our children don’t have to get. I cared for children who died of measles during the last epidemic in this country in the late 1980s — sadly, those deaths were all preventable by vaccines.