Autism And Vaccines: No Need To Worry?

There's a new McCarthyism spreading like wildfire in America, but this time it has nothing to do with Communists, and it's doing more to harm America's youth than the Reds ever did.

This time, it's the model and actress Jenny McCarthy that you should be afraid of.

McCarthy is the de-facto spokesperson in the United States for a growing activist group collectively referred to as the "anti-vaccine movement" (herein referred to as the "AVM"), usually simply called "anti-vaxxers" by their most vehement of critics. The AVM holds a number of positions which are scientifically contentious, but are also picking up a great deal of steam with parents in this country.

In 2005, McCarthy's son was diagnosed with autism, and since then she has been a highly-visible proponent of the idea that the measles-mumps-rubella (MMR) vaccine causes autism in children.

This is an idea that has been kicking around for over a decade, ever since 1998, when British journal of medicine The Lancet published a paper by Andrew Wakefield that apparently showed a causal link between early-childhood vaccinations and autism.

Wakefield's research was shown to be fraudulent in 2009, and the paper has since been retracted by The Lancet. Though Wakefield continues to defend his research, there has yet to be a study which has been able to verify the results of the Wakefield paper. Wakefield himself has been banned from practicing medicine in the United Kingdom as a result of his fraud. This seemingly crippling blow this has not stopped or even slowed the anti-vaccine movement, who continue to cling to the idea that vaccination causes autism.

Humans, at least in the West, have known about inoculation since the late eighteenth century, when Edward Jenner infected children with cowpox in order to protect them against smallpox, but the first great vaccines were not developed until the middle of the twentieth century. When Jonas Salk created the first polio vaccine in 1955, the world changed. No longer did children have to live in fear of that crippling disease -- now a drop of an inexpensive oral vaccine is all that's needed to prevent it. Thanks to vaccination, in 1979 the World Health Organization declared that smallpox, a disease which had terrorized humanity since 10,000 BC, was gone for good. Vaccination has since been considered one of humanity's greatest scientific accomplishments.

It was during the late 1960s when the MMR vaccine was developed. Before the vaccine, hundreds of thousands of children in the United States contracted measles every year. Now, this deadly disease -- about 450 children die of measles every day -- is practically eliminated in the U.S. Or at least it should be. Since McCarthy and others began loudly proclaiming that vaccines cause autism, many parents in the U.S. have been opting to withold the MMR vaccine, among others, from their children. This year, the Centers for Disease Control reported that the United States saw the largest measles outbreak in fifteen years, and according to the CDC, most cases occurred in the unvaccinated.

So why would parents withhold a potentially lifesaving vaccine from their children? Rates of autism, a behavioral disorder which manifests in early childhood, have been skyrocketing in the United States since the late nineties. According to Department of Education data, in 1996, there was less than one autistic child for every thousand children in America. Now, that number is above five. This rise in diagnoses is largely attributable to increased awareness about autism, and changes in diagnostic practises -- there's little evidence that autism's actual prevalence has increased -- but the AVM is quick to characterize autism as an "epidemic," and parents who are terrified that their child might be the next to be diagnosed are eager to latch on to the MMR vaccine hypothesis.

People like Jenny McCarthy and her comrades are not helping anyone. The anti-vaccination movement cultivates an anti-science environment where pre-existing notions are reinforced and any dissenting voices are silenced. Skeptics have been forcibly removed from autism conventions for raising questions about the vaccination-autism link. There's even a children's book coming out in Australia entitled "Melanie's Marvellous Measles," which paints measles as a wonderful and magical experience for every child to experience. In reality, one person in every 2,000 who contracts measles will develop brain inflammation, and ten percent of those people will die, and forty percent will come away with irreversable brain damage. Hardly magical.

Perhaps most saddening, though, is that McCarthy's movement isn't doing anything to help the state of autism research, when the ostensible purpose of the whole movement was to stop kids from getting autism. If anything, it's actually hurting it. The hysteria around vaccines has for years distracted both attention and money away from studies and groups doing actual research into the cause of autism.

Although MMR is the most commonly implicated vaccine, the AVM also points the finger at other substances, such as thimerosal, a mercury-based preservative used in many vaccines prior to 1999, when it was phased out of vaccines for fear that it caused autism. This action by the CDC was merely precautionary, but has led to over a decade of anti-vaccination proponents misconstruing the discontinuance of thimerosal's use to mean there must be some link between it and autism. You may have heard the idea that the "mercury in the MMR vaccine" causes autism, but amusingly, there never was any mercury in that vaccine to begin with. Thimerosal can't be used in a live-virus vaccine like the MMR shot, and it never was. Studies were not performed regarding thimerosal and autism until 2003 – four years after its removal – at the earliest, and the scientific consensus is that there is no link between thiomersal and autism. Autism rates have indeed continued to rise even after its removal from vaccines.

Another hypothesis posits that it's the volume of vaccines given in early childhood is what causes autism. This is called the ‘vaccine overload' hypothesis. It's impossible for vaccines to overload the immune system, and in any case autism isn't mediated by the immune system at all: it's a neurological disorder. On top of that, a 2002 study in Pediatrics shows that although the number of vaccines administered now is higher, more efficient manufacturing means that the load on the immune system from today's fourteen vaccinations is only about ten percent of the seven that were given in 1980.

Parents who neglect to vaccinate their children aren't just putting their own progeny at risk. To understand why the anti-vaccination movement is frightening to those who don't belong to it, one has to understand a couple of lesser-known principles of vaccination. The first is that vaccines aren't one hundred percent effective. A very tiny percentage of those who receive the MMR vaccine -- 5% after one dose and 0.3% after the second -- are not immune to the disease, despite recieving the vaccine. There is also a further group who are unable to receive the vaccination due to allergies. How do these people keep from getting sick?

Via a concept called ‘herd immunity.' If the vast majority of a population are immunized, the remainder who are unable to receive the vaccine are protected because there's no vector for the disease to enter the population. When the rate of vaccination starts to decline, however, it becomes more and more likely that a disease like measles gets introduced. If your unvaccinated child gets measles, and a kid at their school to whom the vaccine didn't take catches it, you've not just hurt your own child, but another parent's as well.

Vaccines are safe. They do not cause autism. When examing the scientific evidence, it's clear. According to a meta-analysis (a study of studies) published in the journal Clinical Infectious Diseases, "Twenty epidemiologic studies have shown that neither thimerosal nor MMR vaccine causes autism. [...] These studies, in concert with the biological implausibility that vaccines overwhelm a child's immune system, have effectively dismissed the notion that vaccines cause autism. Further studies on the cause or causes of autism should focus on more-promising leads."

If you have children or are planning to in the near future, vaccinate them. You won't just be protecting them from potentially-deadly disease: you'll be doing society at large a favor, as well.