Do Vaccines Cause Autism?

In particular, there is no evidence that the trivalent measles, mumps, rubella (MMR) vaccines are in any way connected to pervasive developmental disorders (PDDs) like autism. This week the prestigious British medical journal, The Lancet, retracted a 1998 article that has been at the center of controversy over vaccine safety since it was published. The journal editors cited lack of approval from ethics committees for the procedures involved in the research, and the fact that "several elements" of the paper were "incorrect" in its February 2 statement.

Other studies have been done in the interim, and health professionals have emphasized that no research to date has shown a link between vaccines and autism. One recent study was actually conducted at the same facility as the one mentioned above. It concludes that if there is any link between autism and the MMR vaccine, "it is so rare that it could not be identified in this large regional sample." Most significant in its discussion of a group of almost 500 randomly selected children with autism spectrum disorders is this:

"There was a steady increase in cases by year of birth with no sudden "step-up" or change in the trend line after the introduction of MMR vaccination. There was no difference in age at diagnosis between the cases vaccinated before or after 18 months of age and those never vaccinated." ("Autism and measles, mumps, and rubella vaccine," emphasis mine)

MMR Vaccine Scare

When the Wakefield study was first published in 1998, it created immense fear in parents of small children. Faced with the fear of a lifelong disability that seemed to be growing in incidence to epidemic proportions, versus childhood diseases that today we tend to minimize, a significant number of parents opt not to vaccinate their little ones.

Fear of the MMR vaccine has generalized to fear of all vaccines, as well as a distrust of the companies that manufacture them and the health authorities that advocate their use. This was seen over this past fall and winter, over the H1N1 influenza vaccine.

While many parents did vaccinate themselves and their children, a number of people feared the vaccine was too quickly produced and not adequately tested. Thimerosal, used as a preservative in the multi-dose vials, is also subject to controversy and connection with autism. There was particular concern over pregnant women who feared harming their unborn babies with the vaccine, as late-term pregnancy puts a woman at elevated risk for influenza complications.

Relying on Herd Immunity

Some people who refuse vaccines rely on a phenomenon known as herd immunity. The premise is that an unvaccinated person is protected from contagious disease, if the people around him are vaccinated. This is an important source of protection, when an individual's state of health is fragile and he cannot be vaccinated. Certainly, a person who is at risk is better protected from communicable disease if the members of his household and any regular contacts like care givers are vaccinated.

When it comes to non-vaccination for philosophical or religious reasons, herd immunity can become less reliable. This is especially true if whole communities of people opt not to vaccinate, and spend a good deal of time together. All it takes is contact with one infected person to spread disease through the entire community.

Herd immunity for different illnesses varies, so it's not the same for every disease or in every population. The threshold is generally fairly low for diseases like mumps (75 to 86 percent.) For whooping cough, or pertussis it can be from 92 to 94 percent. For measles it is anywhere from 83 to 94 percent. ("Herd immunity")

When parents began to doubt the MMR vaccine, vaccination levels in the UK plummeted. Parents in Europe and North America abstained from vaccines, though to a lesser extent. In some areas vaccine levels fell below those required for herd immunity. Outbreaks of both measles and mumps have now been seen as a result, affecting the UK, US and Canada.

An Unlikely Prophet for the No-Vaccine Movement

Andrew Wakefield has become a figurehead for those who hold not only MMR, but all vaccines suspect. He finds himself in the company of celebrities like Jenny McCarthy and husband Jim Carrey. In actual fact, Wakefield is not opposed to vaccination. Rather, he states that his concern was always about a single vaccine formulation only: the trivalent MMR vaccine.

"I am not anti-vaccine" he said after resigning his post in the UK, "and still think children should be vaccinated, but not with this formulation." ("Controversial MMR-autism investigator resigns from research post")

Most ironic for the anti-vaccine movement that has built its arguments about the potential hazards of vaccines in part on Wakefield's now retracted paper, is the fact that the good doctor himself is connected with a rival measles vaccine, for which the Royal Free Hospital applied for a patent almost a year before the Lancet paper was published. In the patent application, Wakefield claims that his vaccine is a safer alternative to the trivalent vaccine, and that it can also cure both inflammatory bowel disease (IBD) and pervasive developmental disorders like autism. ("Revealed")

Sources:

"Autism and measles, mumps, and rubella vaccine: no epidemiological evidence for a causal association" Brent Taylor FRCPCH, et al (Lancet)

"Controversial MMR-autism investigator resigns from research post" Sarah Ramsay (Lancet)

"Herd immunity" Wikipedia

"Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children" AJ Wakefield FRCS, et al (Lancet)

"Lancet retracts controversial autism paper" Dan Childs and Lauren Cox (ABC)

"Lancet retracts flawed autism study, but paper's legacy lingers, experts fear" Helen Branswell (Canadian Press)

"Lancet retracts study linking vaccine to autism" Avis Favro (CTV)

"MMR vaccine controversy" Wikipedia

"MMR vaccine: Who's to blame?" CBS

"Retraction-Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children" The Lancet

"Revealed: the first Wakefield MMR patent claim describes 'safer measles vaccine'" Brian Deer

"Vaccine link to autism retracted" ABC