Really, it’s not the vaccine…
Two weeks ago, the New York Times published an article called “Debunking an Autism Theory”, which traced the history of the purported link between autism and the mumps, measles, and rubella (MMR) vaccine. It was great timing for me, because I was teaching about the scientific method in one of my classes, mainly comprised of college sophomores. This is the way science is supposed to work, I told them. Someone raised the question of whether a normal practice was putting kids at risk, which is something we’d really want to know if it were true. They did a study—perhaps not the greatest study, but it was a start—and then other researchers joined in. But after the first study raised the question, no evidence could be found to support the idea that the vaccine cause autism. Study after study was conducted, hundreds of thousands of children were examined, and there was just no evidence for this claim. Finally, according to the Times, an attempt to repeat the original study resulted in failure. Science did what it was supposed to do: asked an important question, considered it carefully, collected objective data, and came to a conclusion. The conclusion is clear: the MMR vaccine does not cause autism.
One of my students raised her hand and said, “But I have a cousin who believes it does. She’s home-schooling her kids just so they won’t have to get the vaccine. She’s never going to believe this.” And my student is right. The human mind doesn’t latch on to statistics the same way it does to a vivid anecdote about a child who was ‘fine’ one month, and then diagnosed with autism the next, just after receiving the vaccine. We overweight vivid risks (the pain of an autism diagnosis; the chance our baby will never grow up to say “I love you, Mom”) and we minimize the more diffuse risk of a non-immunized population. We coast on the confidence that if all the other kids get the vaccine, the risk to our own child will be low, not noticing that more and more parents are avoiding the vaccine.
I think the fundamental problem arises from what psychologists call an “illusory correlation”, the mistaken impression that two things go together that often arises when vivid, distinctive events are paired. One of the hallmarks of autism is delay of speech, which cannot be noticed in kids before 12-18 months of age because kids are just not expected to speak earlier than that. The MMR vaccine is typically administered between the ages of 12-15 months. So if a parent receives a diagnosis of autism for her child, she will naturally cast about for an explanation. It’s hard to accept that some things just happen, so we look for a way to explain it, to make the universe a little less random. What was it that happened just before the diagnosis? The child received the vaccine. It’s easy to believe that’s the cause, and hard to reject that idea for the explanation that you just got really unlucky. It’s perhaps even harder to recall all the people who got the vaccine and did not develop autism, which is one of the things you’d need to do to consider the probability of this link. But who could summon the emotional detachment necessary to sift through case after case of your friends’ and neighbors’ children who will not face the challenges your own child will? It would not be easy, or even possible, for most of us.
Still, the evidence against this claim is strong. For instance, for many years the proposed mechanism was Thimerosal, a form of mercury, used as a preservative in the vaccine. So, just in case, the compound was removed from vaccines. Since 2001, vaccines for children younger than 6 years of age have contained no Thimerosal. If this compound was causing autism, you’d have to expect the number of diagnoses to drop, but that hasn’t happened. The rates of diagnosis have actually increased since 2001. Another way to look at it is this: when you compare large numbers of children who have been vaccinated to large numbers who haven’t, you don’t see a difference in the incidence of autism, and if the vaccine really was the problem, you should. That’s why scientists come out and say with confidence, “There is no evidence of a causal link,” which in science-speak is extremely strongly worded. But to the average person, perhaps “there is no evidence” is heard as “well, you just didn’t find it yet.” And that gives a very vivid fear room to play.
Science has served the public well when it comes to autism. Fifty years ago, the mental health community believed that autism was caused by “refrigerator mothers”, women who could not show enough affection to their children. If there is a crueler thing than to blame and illness on a parent for not loving enough, I have a hard time imagining what it is. Since that time, we’ve learned a great deal about the spectrum of autistic disorders, and about specific risk factors and treatment possibilities. It’s unfortunate, I think, that the myth about the MMR vaccine continues to get so much attention when there is real scientific work going on that has the potential to be so beneficial to the children diagnosed with autism and to their families.
marcy Said,
October 2, 2008 @ 7:13 pm
Great blog, great post!
To follow on to your last point, it’s also unfortunate that the angry parents who believe vaccines made their kids autistic keep lobbying for more research into what they insist is a plausible idea – and this diverts money from being spent on research that could actually help autistics. I know CDC itself has done at least four studies (two of them still in process), and there have been scores of others.
Kris Vasquez Said,
October 5, 2008 @ 11:08 am
That’s definitely an important point when it comes to all things skeptical. Too often, I think, skeptics are viewed as cranks who don’t believe in anything, and who are trying to spoil the fun of open-minded people. What isn’t apparent, a lot of the time, is the opportunity cost of mistaken beliefs. For every dollar spent on classical music CDs in a mistaken attempt to raise a baby’s IQ, that’s less money available for things that would really be beneficial to the child’s development. The time spent teaching pseudoscience in classrooms means less time for teaching real science that can lead to solutions for society’s problems. There really is a significant cost to uncritical acceptance these ideas. Thanks for pointing that out.
Squillo Said,
October 5, 2008 @ 3:18 pm
Great post, except you’ve conflated the MMR issue with the Thimerosol issue. MMR never contained Thimerosol. The MMR controversy arose when gastroenterologist Andrew Wakefield published a study (subsequently retracted) in The Lancet that purported to identify a new syndrome of gastrointestinal disorders in a small group of children with autism. At a subsequent press confrence, Wakefield suggested splitting the combined vaccine into three separate vaccinations to avoid a possible “environmental” trigger for the syndrome, until a connection to MMR vaccination could be ruled out. The reporting surrounding this event caused a subsequent drop-off in MMR vaccination rates in the UK.
The MMR-autism controversy may have been the spark that set off the race to connect vaccination to autism, and led to the subsequent focus on Thimerosol. (And antivaccinationists’ new bugaboo, aluminum.)
Kris Vasquez Said,
October 6, 2008 @ 12:58 pm
Thanks for the correction. I have read about the Thimerosal in MMR vaccines in so many places that I didn’t question it. Bad practice for skeptics, isn’t it?
If you are correct (and you sound like you know your stuff, but having learned a lesson here, I will follow up on the history of the Wakefield article to convince myself), the logic of the counterargument remains essentially unchanged. Autism rates have increased while the formulation of the MMR vaccine remained the same, and while Thimerosal was removed from other childhood vaccines. There is no way to draw from that pattern the conclusion that either the MMR vaccine, or the Thimerosal in other vaccines, is causing autism. One argument might be that cases are now being diagnosed for children who, a few decades ago, would not have been labeled autistic. But generally the people who fear a vaccine-autism link predicate their arguments on the belief that the real incidence of autism, not just the rate of diagnosis, is rising. If that is true, we certainly need to address it, but not by chasing phantoms.
Squillo Said,
October 7, 2008 @ 9:29 am
Indeed, the counterargument is the same. The folks who are really invested in the vaccines-cause-autism keep moving the goalposts: It’s the measles virus in the gut; No? Then it’s the Thimerosol. No? How about aluminum? “Overloaded” immune system? What about the “antifreeze?” Now, thanks to the ruling on the Poling case, we’re going to have a glut of people claiming underlying mitochondrial disorders were triggered by vaccination.
The Mainstream Parenting blog http://mainstreamparenting.wordpress.com/)–which was how I heard about y’all–has some excellent, and easy-for-us-liberal-arts-types-to-understand explanations of the issues.
Chris H. Said,
October 12, 2008 @ 7:26 pm
Squillo said “I have read about the Thimerosal in MMR vaccines in so many places that I didn’t question it. Bad practice for skeptics, isn’t it?”
It is a very common mistake, and sometimes I figure someone has not looked into the issue much when they make that mistake. :-p
A good quick way to get up to speed is to read this book that was part of the Scienceblogs book discussion:
http://scienceblogs.com/bookclub/autisms_false_prophets/
I was one of the lucky 50 to get a free copy, but I am sure it is in your local library.
Chris H. Said,
October 12, 2008 @ 7:34 pm
(2nd try, it might have a browser setting or you are very strict on URLs, if this is a double, sorry, and I screwed up the quote… need wine, need sleep!)
KrisV said ” I have read about the Thimerosal in MMR vaccines in so many places that I didn’t question it. Bad practice for skeptics, isn’t it?”
It is a very common mistake. I usually figure that those who say “the thimerosal in MMR” are not as immersed in the issue as many of us are. :-p … Which is probably a good thing.
A good way to get up to speed, and to have a good read is to pick up a copy of the book recently discussed on Scienceblogs:
http://scienceblogs.com/bookclub/autisms_false_prophets/
I was one of the lucky 50 who got a free copy, which I hope to give away at our local skeptic meetup.
Dr. Chuck Said,
November 23, 2008 @ 5:45 pm
Confusing the “MMR causes autism” and the “thimerosal causes autism” claims is very common. In fact, in the infamous Jenny McCarthy appearance on Oprah, a CDC response to the thimerosal issue was interjected into the conversation about MMR. Of course, no one on the show noticed, even the “expert”, Jenny McCarthy.
Also, the primary reason thimerosal was removed from vaccines was to reduce the total lifetime exposure to mercury, not necessarily due to the autism scare. In addition, the birth dose of Hepatitis B vaccine exceeded the government determined safe exposure level to mercury.
Michelle Said,
January 15, 2009 @ 2:51 pm
Interesting.
I can only say that I consider myself very rational, a
libertarian, mother of three, take good care of myself etc. Regarding the whole topic of vaccines…
When the doctors came to me the day after giving birth wanting to
give my baby a shot for Hep B and smear Eurethromyacin in her eyes- I was shocked. I asked the nurse what this was about- she said it’s ” a public health measure to prevent babies from getting serious eye infections from gonorrhea/chlamydia bacteria.”
I said I’d been tested during my pregnancy, niether my husband or I
visited any prostitutes, I knew we didn’t have it. She said it was
hospital policy.
Thus began my journey at questioning what the AMA/FDA tell us is
right.
I’m not a crunchy granola woman, I’m not Jenny McCarthy, but the amount of aluminum and formaldehyde used to preserve vaccines is far above what they tell us an ADULT should have in their system, let alone a child.
This is not to say that I don’t believe in vaccinations or big
medicine. I think the’re very valuable. I also think that someone
somewhere is making a great deal of money off of them, as there are
now three times the amount of vaccinations than what I received in the late 60’s. So what I’ve done is spaced the immunizations out a bit more, waiting for my children to hit at least 50 pounds before I
start- and then stretching it out longer over the years. We haven’t
visited darkest Africa (yet) or the streets of Tehran- our little
community in Larchmont is fairly isolated and safe. And my children are happy and healthy, as am I.
Blind trust in any organization is always dangerous- do your own research and come to your own conclusions. Remember Gardasil? Here are some interesting things that have happened with it in the last few years;
“The National Vaccine Information Center yesterday warned state
officials to investigate the safety of a breakthrough cancer vaccine
as Texas became the first state to make the vaccine mandatory for
school-age girls. Negative side effects of GARDASIL, a new Merck
vaccine to prevent the sexually transmitted virus that causes cervical
cancer, are being reported in the District of Columbia and 20 states,
including Virginia. The reactions range from loss of consciousness to seizures. “Young girls are experiencing severe headaches, dizziness, temporary loss of vision and some girls have lost consciousness during what appear to be seizures,” said Vicky Debold, health policy analyst for the National Vaccine Information Center, a nonprofit watchdog organization that was created in the early 1980s to prevent vaccine injuries.” – Gregory Lopes, The Washington Times, Feb. 3, 2007
“Lawmakers should have been allowed to hear from doctors, scientists and patients before the state implemented such a sweeping mandate, said state Sen. Jane Nelson, chairwoman of the health and human services committee. “This is not an emergency,” said Nelson, adding that she plans to ask Attorney General Greg Abbott for an opinion on the legality of Perry’s order. “It needs to be discussed and debated.”
Three other Republican lawmakers filed bills that would override the mandate, and several others were working on similar legislation.” -
Liz Austin Peterson, Associated Press, Feb. 5, 2007
“Dr. Patricia Sulak, a professor of obstetrics-gynecology at the Texas A&M Health Science Center College of Medicine, said health-care providers she knows were shocked by the order. “It’s such a new vaccine — they haven’t had time to explain it to patients,” said
Sulak. “I think everyone was happy with the CDC’s Advisory Committee for Immunization Practices’ recommendation that it be routinely given.
But this makes it seem like it’s being shoved down people’s throats.”
Hinchey [president- elect of Texas Medical Association] and others
emphasized that although the vaccine is considered safe, there are
questions of whether there is enough experience with it to warrant a
mandate. They say that some girls eventually may experience rare
adverse effects not yet identified.” – Todd Ackerman, Houston
Chronicle, Feb. 7, 2007
Read this link;
http://www.fwdailynews.com/articles/2007/03/14/online_features/hpv_vaccine/hpv01.txt
Dr. Chuck Said,
January 29, 2009 @ 8:41 pm
Michelle brings up a few points that I often hear from parents or see on various web sites.
The first is why a particular public health intervention (immunization, antibiotic eye ointment, etc.) needs to be given to everyone and not just those at risk. I like to think that most of my patient’s parents don’t practice risky sexual behaviors, but I am quite often surprised. If physicians don’t have a policy to protect all infants with erythromycin eye ointment, then we are put in a position to decide who IS at risk. “You look like you might be sexually promiscuous, so I’ll give your child the ointment, and not the baby next door.” I live in a city of highly educated parents with mean household incomes in the $65,000 range. It is also a city that has seen a major resurgence in syphilis cases in the past few years. Erythromycin ointment if a safe, effective means of preventing eye infections that can rapidly lead to blindness. The proven benefits of universal treatment of infants with this ointment far outweighs the risk.
As to the risk of the Gardasil vaccine, “young girls experiencing severe headaches, dizziness, temporary loss of vision and loss of consciousness” is another way of saying they are fainting after being poked with a needle. For a summary of the current data on adverse events related to this vaccine, which has to date been given to over 20 million patients, see this link http://www.cdc.gov/vaccinesafety/vaers/gardasil.htm.