The recent addition of Jenny McCarthy to The View TV show has me and my fellow scientists riled up. It concerns me that someone with such dangerous views on vaccines and autism will have a national pulpit from which to spew her pseudoscience regularly. This is a post I've been working on for quite some time.
I've had several conversations recently with people touting that vaccines cause autism. I thought I would write down some of their arguments, my thoughts on the issue and tell you why vaccines DO NOT cause autism. While I am not taking the time to include references in this post, I do have the references available, so please leave a comment if you would like further information.
My credentials: I am a PhD in cell & molecular biology from an Ivy League school. I have an extensive background in developmental biology and embryology, but I do not study autism. My information comes from reading peer-reviewed, highly respected scientific journals.
Firstly, what are vaccines?
Vaccines are pieces of generally inactive virus that are injected into the human body to cause a minor immune response. The human immune system responds by making antibodies that recognize the viral particles as "foreign invaders". The viral particles are destroyed by the immune system, and the amazing thing? Your body keeps a few of those antibodies around, just in case you ever come across that virus again! How cool is that? So, the next time you are exposed to the virus, you are able to immediately recognize it as "bad", ramp up your antibody production, and kill it before it causes the disease. This is the simplified version of a vaccine scenario. The actual process itself is much more complex, and some viruses can be stubborn. Also, we sometimes need "booster" shots to boost our immune response to the virus to ensure we are immune to it.
Why are vaccines important?
Vaccines are important for two reasons: they prevent disease (often devastating, highly communicable and contagious disease) and they protect the population from the spread of disease. Vaccines establish "herd immunity". Herd immunity (herd meaning a population of humans, and immunity meaning resistance to a particular disease) is important in preventing flare-ups of a disease. Generally, to prevent infection of a population, we need to maintain about 90-100% vaccinated population, meaning that 90-100% of people need to be vaccinated. This has occurred with the polio vaccine. Children are usually vaccinated against polio at a young age and because of this, polio has been eradicated in the US. The herd immunity against the measles is quite a bit lower since a lot of people refuse to vaccinate their children. This leads to flare ups of the measles, usually in populations of young children. More on that later. Therefore, vaccines are two things: an issue of personal health to prevent disease AND an issue of public health, to prevent disease in the population. This is why vaccines are normally mandated prior to children entering school.
Do vaccines fail? What about people who don't get vaccinated?
So, here's the clincher: vaccines don't always work. Sometimes, people just don't have the proper immune response, making them more susceptible to disease. Also, there is a very small portion of the population that should NOT have vaccines. These are people who may be immune compromised, or may have a genetic disorder, or an allergy to a component in vaccines. These are also children (usually babies) that cannot be vaccinated yet because they are too young. This also includes some older folks who might not have the strongest immune system to receive a vaccine. The people who are unable to take vaccines can compromise our herd immunity. However, if the majority of the population that CAN get vaccinated DOES get vaccinated, then we as a population can protect those people. Therefore, a vaccination not only protects YOU from getting disease, it can also protect your child, or your grandparents as well.
What is autism?
This is a harder question to answer. Autism is normally a syndrome that affects the social abilities of individuals. Meaning, individuals may not be able to communicate verbally, and may not pick up on subtle social cues, like body language or facial expressions. Autistic individuals often are quite intelligent, can perform well on tests, in mathematics or science. As with all syndromes, there is a broad spectrum of symptoms associated with autism, and not every individual exhibits all symptoms. Autism occurs most highly in boys, suggesting there may be some sex-related aspects of the disease. There is no known ONE cause of autism, but it has been linked to environmental factors and several regions of the genome. Autism is extremely common, occurring, to some degree, in nearly 1 in 88 male children (something like 1 in 121 female children).
OK, now that we have some background, here are some of the arguments that I have heard from people saying that vaccines cause autism. I'll go through them and rebut them as best I can.
1) A paper was published that linked autism to the MMR (measles, mumps, rubella) vaccine
This is a true statement. Dr. Andrew Wakefield published a study of 12 severely autistic children and linked the onset of their neurological symptoms with the MMR vaccine. It was later found that Wakefield had actually FALSIFIED the majority of his data. Multiple other labs could not replicate his findings. The paper was retracted, meaning the journal The Lancet could no longer guarantee that these findings were accurate. Therefore, this paper was clearly falsified, these authors lied to the public about their findings and a link between MMR and autism has never been shown.
2) It's not the vaccine, it's the additives within the vaccine.
Many vaccines contain preservatives in them to extend their shelf life. One of the more common additives is thimerosol, which is a form of mercury. Thimerosol exists in a conformation that makes it less "bioavailable". What does that mean? Well, some things are readily absorbed by the body and can cause harm. Other things are not so readily absorbed. Thimerosol is not so readily absorbed by the body. There is very little thimerosol in most vaccines. Notably, elimination of thimerosol from the MMR vaccine HAD NO EFFECT on rates of autism in Japan. Clearly meaning that thimerosol cannot be causing autism. Other additives, like aluminum, are slightly more harmful, but exist in such low doses in vaccines that it's unlikely those could be causing autism. You are exposed to much more dangerous chemicals in the pesticides on your food or the chemicals in your home.
3) There is a vast conspiracy of drug companies just wanting to steal your money.
So, drug companies don't actually make money off your vaccine. Most vaccines are well past their patent date (with the exception of the HPV vaccine), meaning they can be made generically. Drug companies actually get a bit of a tax break for making vaccines (in the US) because the cost of manufacturing the vaccine is higher than what the consumer pays for the vaccine. Also, I am just going to address this idea of a conspiracy once: THERE IS NO CONSPIRACY. The idea that drug companies, scientists, doctors, nurses and all of the scientific community would get together to delude the public is inane and impossible.
4) Scientists know something that you don't know. They are hiding the TRUTH.
This falls under the conspiracy category again. But also, there is something amazing and wonderful about science. It's public. In order to get jobs, in order to get promotions, in order to remain in good standing with our peers, we must publish our work. Work that is supported by the US government is REQUIRED to be open access (free to the public) after one year. Meaning, any person can read scientific articles, look at published data, and form their own opinions. The science is out there, ready to be read. The problem with science is that we don't know all the answers. We certainly don't know what causes autism, and why it occurs at such a high rate. We even don't fully understand how the immune system works, or how vaccines work. This can lead to conflicting information, differing opinions, but usually the opinions are subtle, and don't actually revolve around the idea that autism could be caused by vaccines.
5) But this celebrity, famous doctor, etc told me on TV that I shouldn't vaccinate my kids because it causes autism.
Look, just because people are LOUD doesn't mean they are right. Celebrities, famous doctors, etc are not your family doctor. They don't know your situation and they have more money than they know what to do with. Unfortunately, we worship at the altar of celebrity and pay no attention to our scientific experts. I would encourage anybody to research what celebrities are saying BEFORE deciding how you should live your life. I do, however, have to stress the importance of picking a reputable source - requesting literature from your doctor, reading reputable scientific journals or magazines (like Science, Nature, The New England Journal of Medicine, or even Scientific American for the lay person). The nice thing about science journals is that the majority of the articles published in them are peer-reviewed. Meaning, several scientists (other than the authors) have read through the article to ensure it is accurate. Reading a random website or pamphlet is misleading and often contains false information.
OK, then what COULD cause autism?
Well, honestly, I'm not sure I am qualified to answer that question. Here's what I can tell you. The nervous system is incredibly complex. Your brain contains millions of neurons that can simultaneously allow you to think, type, write, be hungry, breathe, beat your heart, move your leg, swallow, produce bile, digest your lunch, move your colon (and on, and on, and on....). Your brain is a million times more complex than the computer you are using. Here's the thing: science has been amazing at studying neurons individually. We can grow them in dishes, we can kill them to see what happens. However, how neurons process information, store it, and access it is still a mystery. And generally, the way things go is that once we figure out how things occur during normal development, we can start to figure out how things can go awry during development. There are a number of things that complicate the issue.
1) Misdiagnosis: Autism is called a "Spectrum Disorder" for a reason. Patients present with a large number of different types of symptoms, making diagnosis complex. There is no one test that says, yes, this person is autistic. Because it's a neurological disorder, many other things can look like autism. One of the more famous cases is Jenny McCarthy's son who has a rare disorder that looks like autism, but apparently can be controlled by diet and some other lifestyle changes. Misdiagnosis leads people like Jenny McCarthy to think that they can cure autism by holistic approaches and lifestyle changes, when her son was not autistic to begin with. Granted, the medical community needs to get better at diagnosis (and I honestly think it is), but right now we have to deal with some misdiagnosis in the community.
2) First presentation of the disease correlates with vaccine administration. Parents often notice social changes in their autistic children around 18-24 months of age. This appears to be an unfortunate correlation with vaccine administration, and numerous, extensive studies have failed to show a link between autism and vaccines. However, what IS happening during this time period is an ENORMOUS amount of growth in the child's brain. The two times in life after birth when your brain is expanding? Around age 2 and right around puberty (which is why you still remember ALL the lyrics to that NKOTB song you haven't heard in 20 years). Around age two, your brain is undergoing an enormous expansion, setting up networks for speech, to create memories, to learn language (including subtle body language) and to make complex connections among numerous things (like recognizing that words like "dog" mean the animal dog, but also the cartoon character "Goofy" etc). An enormous foundation is laid down at this time point in childhood, and if the proper connections aren't made, then disorders may arise. We still don't understand how all the connections are made, which ones are important for social behaviors, and how to rectify the situation if we can. It seems like the best treatment right now is early intervention, which actually may "train" other regions of the brain to control social skills. However, we still have a long way to go.
3) Some children begin speaking and being social and then regress to an autistic condition, also correlating with vaccine administration. Regression is another thing that is not well understood. During development, "building a brain" is incredibly complex. Neurons need to navigate their environment, make connections where appropriate, and then they are "pruned". Sometimes, this means the connections are removed, other times, this can mean that some connections are strengthened. Think of the electricity in your house. Initially, let's say that your entire house is electrified. A giant net of wires envelops your whole house, but there are no plugs where you can plug in your TV. Gradually, over time, the net is pruned (like a bush), and some wires are strengthened, eventually resulting in your current house with several, strong plugs in convenient places, so you can use electricity efficiently, access it when you want it, but you aren't electrocuted when you plug things in. This is sort of like the developing brain. Connections need to be made in the right places, and then they need to be pruned so only the strongest remain. When this doesn't occur properly, then disorders, such as autism, may arise.
4) Correlation of doctor's visits with onset of autism. Just to emphasize, correlation does not equal causation. However, many people will start to notice signs of autism right around the time they take their kid to the doctor. This is probably just one of those normal phenomena where people are looking for any questions they might have about their kid's growth and development. Similarly, doctors may bring parent's attention to certain things, ask parents to look out for certain behaviors, because, again, early intervention and therapies are the best way to treat autism.
5) Some people die from vaccines. This is, unfortunately, entirely true. Some kids are born with particular problems processing vaccines or having proper immune responses. Normally, this is a really, really tiny portion of the population. Some vaccines can cause adverse affects in a small percentage of people (normally, this is something like swelling, fever, pain in the area of injection). Very rarely does this cause death. However, there are particular disorders that, if not diagnosed, can cause death in people who receive vaccines. Because this is a small percentage of the population, this is generally seen as a manageable loss in the population, especially when you think about how many people would be affected if the population had polio. However, this is such a sad consequence, it's hard to see how losing even ONE kid is OK. We have lots of public policies in place to ensure that vaccines are safe before they are released to the public, and there are many, many ongoing studies to ensure vaccines remain effective.
The consequences of not vaccinating your kids and family.
On an individual level, there are usually few consequences to not vaccinating your kids. More than likely, the rest of the community around you is vaccinated, and that herd immunity will protect your family from catching most diseases. However, there have been increasing numbers of communities reported around the world where people can catch diseases that have been nearly eradicated by vaccines. In my community in Northern CA, there have been numerous outbreaks of whooping cough, which is fatal to kids under 1 year old. Thankfully, only 4 kids died last year (which is actually a MUCH higher percentage than people who would die from vaccine administration), and the daycares our kid will go to have nearly 100% vaccination. However, this is not always the case. Most diseases are hardest on the very, very young and the very, very old. In the young, these diseases can cause permanent damage to developing organs (such as the inner ear damage sustained by my mom when she got the measles). So protecting those parts of the population often requires a community effort. Very rarely are you asked to do something for the good of the community. Vaccination is one thing you can do to ensure the health of your community.
As a scientist, what are you doing to try to reduce the risk of autism in your kids?
Well, here's my opinion (and it's only an informed opinion - nothing more, nothing less). I think that some autism is caused by genetics. It's likely caused by changes in multiple regions of DNA and it likely extremely complex. However, it still remains that the incidence of autism is highest in the "Western" world - that is, developed countries have a higher rate of autism than other, less developed countries. This could be due to a number of reasons - namely, healthcare in first-world countries is better, so children are more likely to be diagnosed. Secondly, we have access to modern thinking - some third world inhabitants might think of an autism spectrum disorder as a blessing or a curse (for example, have you read The Spirit Catches You and You Fall down? It's about a Hmong girl who presents with severe epilepsy - but her family thinks she is a "seer" and a "blessing"). And thirdly, there could be something about our modern, first-world life that contributes to autism. For me, these boil down to a few things:
1) Pesticides concern me.
I buy my produce from the local farmers market, and hardly ever from the actual market. I buy organic whenever possible, including milk and cheese. Pesticides are often something that looks like a hormone, and will try to mess up things like maturation of insects (remember that they go through pupa stages of growth prior to becoming adult insects). The problem is that these pesticides also muck up animal (and probably human, too) hormone responsive tissues. I would not be surprised to find that pesticides can be the cause of breast cancer or prostate cancer (these are tissues that are highly responsive to hormones). Plus, pesticides are very difficult to wash off of produce - water alone won't do it. And pesticides leech into our ground water and pollute rivers and lakes and the ocean. They are just all around bad things.
2) Plastic concerns me.
I never heat anything in plastic. I have one pan with non-stick coating and I never use it. I don't eat frozen foods that you have to heat in the microwave. I drink out of glass or aluminum containers. I don't drink bottled water if I can avoid it. The kiddo's bottles will be glass, and not plastic. We never store food in plastic containers. Now, the truth is, it's really, really hard to avoid plastic all together. I am not to the point where I will not buy cream cheese or sour cream because it comes in a plastic tub (although, honestly, I don't buy those things very often). I don't buy things in bulk from Whole Foods or bring my own containers to buy meat. These things seem like too big of a hassle for me right now. I do bring my own bags to the grocery store. I do bring my own produce bags to the farmers market (organic cotton - I know, I'm obnoxious!). Some of this is to reduce waste, some of it is my paranoia at putting organic produce into plastic bags. There are several reasons I don't like plastic: 1) it comes from oil and we have enough problems with oil to deal with, 2) it requires a very intense manufacturing process that requires a lot of energy, 3) plastic takes literally forever to break down in our landfills (and, arguably, in our oceans), and 4) many, many chemical by-products are produced by plastic manufacturing, including Bisphenol A (BPA - something that your body thinks is estrogen). These chemicals don't come out of the plastic in the manufacturing process, and can come out into the foods you eat.
3) I will breastfeed my kid.
I know this is not for everyone. And I know that I might have problems and difficulties breast feeding. And I don't think there is any link between formula feeding and autism. And I know that breast milk can have just as many chemicals and pesticides in it as any of these other products. The fact remains that human beings are mammals and we are "supposed" to breast feed our children. This was a major evolutionary adaptation. And here are my thoughts on the process: at least most of the things that I eat will have been processed at least once by my body - perhaps my liver and kidneys can work a little harder to clean out some of these chemicals and that will give my kid a little bit of a barrier - maybe, just maybe - a little bit of protection for the start of his life - from these chemicals and pesticides in the environment and in our foods.
4) I don't use anything harsh to clean my house.
I buy baking soda and vinegar in huge tubs. I use the "Method" brand of cleaning agents, if I need something to clean my bathroom. I do not use bleach. I use environmentally friends soap. Some of this is because of organo-phosphates, which are present in a lot of chemicals we use in, say, bathroom cleaner (and then go on to pollute our ground water). Some of this is due to the fact that these cleaners make me physically ill when I use them. Some of it has to do with the fact that I can recognize chemical names on labels and I know what stuff is particularly nasty. And, no, these things are NOT regulated - these cleaners are NOT safe. Many of them should be disposed of in hazardous waste and are not. In my mind, my Grandma's house was the cleanest I had been in. And these are all the things she used to clean her house. If it was good enough for her, it's good enough for me.
5) I don't use anything like ant spray, roach spray or any pesticides or chemicals in my house.
This probably goes without saying, since I said before I don't like pesticides, but I don't use these things around my house. The two things we have battled against have been ants and fruit flies. Ants will eat a solution of sugar and boric acid, take it back to their nest, and the boric acid will kill the nest (theoretically- sometimes it takes a couple applications). Boric acid is essentially harmless to humans and pets (unless, say, you have a taratula or some kind of bug as a pet). This requires you to live with a trail of ants in your kitchen for a day or two, but it's really not that bad. Fruit flies are even easier to get rid of. Take a coffee cup (or whatever container you have laying around), and put about an inch of apple cider vinegar with a drop of liquid soap in it. Mix it all in. Cover the cup with a piece of paper, and punch a couple holes in the top. Make the holes big enough for the flies to get in, but small enough for them to have difficulty getting out. Our cats usually catch any vermin (mice, rats), and I would NEVER poison those animals because other animals will eat them and be poisoned, too. Traps usually work well for those kinds of animals. Spiders and house flies, I leave alone, or I swat them if they're too creepy. Mostly, Ducky just goes after them and is very proud when he catches one.
6) We eat meat about twice a week.
Again, I don't think this has anything to do with autism, but since I've been pregnant, I just don't like meat that much. It's OK, but it's definitely not my favorite thing. If I could buy a cow from a farmer and know it's life history (and also have a place to store it!), then I probably would do that. However, it's so hard to know where your meat comes from, how it was handled, how many steroids or antibiotics it was given, and how it was treated. It just makes me feel bad, for the most part. Plus, meat is really expensive, and it's more healthful for us to eat less of it (less environmental impact, less packaging, less processing and less energy), so that's been the way it is for a while.
7) I don't chew gum.
Gum is essentially plastic. I used to eat it all the time, after meals, just for a pick-me up. But, now, I just drink water. It's better for me anyways, and it flushes out that after meal taste just as good as gum (if it doesn't, then that means I need to drink more!).
8) I will be careful to look at where my kid's toys come from.
This is another branch of "plastic concerns me". Manufacturing in other countries often cuts corners, uses extremely harsh chemicals, and pollutes the environment. These toys are often plastic, can contain lead paints (or worse...) and are poorly regulated and tested. Plus all these things are cheap and disposable and I hate cheap and disposable (especially when I know it will take millions of years for that stupid McDonald's toy to break down). I realize this is a huge uphill battle, especially when the kiddo starts to recognize ads directed at him. However, I am hoping we can remain conscious of these disposable toys and at least keep them out of his mouth while he's young.
9) I will vaccinate my kids.
This also likely goes without saying, but my kids will be vaccinated, barring any unusual disease or disorder. I will continue to be vaccinated, and my husband will continue to be vaccinated. Our family is committed to stopping the spread of disease, especially in early childhood. If we can prevent one person from getting some terrible disease, then we've done our job.
10) I don't eat processed foods.
I rarely buy mixes, I never buy frozen dinners. Our frozen food is all fresh food that we've frozen. We don't eat a ton of canned goods. Some of the reasons for this is that I just don't find processed foods tasty. I can often make something that tastes better in the same amount of time. Other reasoning behind this is that processed foods contain so much salt that I can't drink enough water to keep hydrated (and being pregnant, this is a huge pain in the butt!). Other reasons for this include the amounts of chemicals in processed foods, how crappy I feel after eating them, and how concerned I am about additives like "flavor enhancers" and high fructose corn syrup.
In summary, autism is an incredibly complex disorder that is not caused by vaccine administration. It likely has multiple causes, many of which are environmental. The vaccine debate has been raging on because the American public has such a poor understanding of science, scientific debate, the scientific method, and statistics, which is what really concerns me. Politicians (or public figures) state that they don't "believe" in science, without understanding that science doesn't require "belief", it requires evidence and logic. I see a widening gap between the American people and scientists (who, granted, are quite poor at outreach and teaching), and an increasing distrust of the scientific community as if we have something to gain from hiding evidence or data from the public. I am hopeful that my contribution, however small, can help to further clarify the scientist's point of view.
Well, there you have it folks - my two cents on the whole autism debate. Thanks for reading, and if you have any questions (or would like to know the sources of my information), I am happy to provide, just leave me a comment.