[...] is Autism Awareness Month and has Rebecca Odes reported yesterday, a new study has been published that suggests a possible vaccine link. A government advisor on [...]

I can’t really tell the veracity of the research because I went to the source article at CBS news and it is just plainly terrible science journalism. It isn’t clear at all from the article what Dr. Ratajczak is actually proposing.

So it will presumably just be another tennis ball to be swatted back and forth by the pro- and anti-vaccine camps.

As presented here and at CBS, this story is confusing at best. As far as I can tell, and as stated above, this is a “review of theories,” not data. It is a theoretical paper proposing causes. Perhaps it suggests a mechanism for a vaccine/autism link, but it does not have any data to suggest that such a link exists. The studies that have looked at real data so far fail to show a link.

I gotta agree with Laura, too. As a dad and former scientist, the quality of writing about science news for parents on Babble is often rather poor.

Everyone knows that “correlation does not equal causation.” But very few people understand what does determine causation.

To determine if Event A caused Disease B, we need to investigate whether it satisfies Hill’s Criteria. These are 9 criteria, most of which much be satisfied before we can conclude that Event A is not merely correlated with Disease B, but Event A actually causes Disease B.

What are the criteria?

1. Temporal relationship: It may sound obvious, but if Event A causes Disease B, Event A must occur before Disease B. The is the only absolutely essential criterion, but it is NOT sufficient. Lay people often erroneously assume that because it’s the only essential criterion, it is the only criterion that counts. For example, vaccine rejectionists often point to the fact that childhood vaccinations usually occur before the onset of autism, but that does not mean that vaccination causes autism. Consider that learning to walk usually precedes autism, but obviously learning to walk does not cause autism.

2. Strength: This is measured by statistical tests, but can be thought of as similar to the closeness of the relationship. Is Disease B always preceded by Event A? Sometimes? Only rarely? In the case of vaccines and autism, vaccines usually precede the diagnosis. However, most children who receive vaccines don’t develop autism. Thus the relationship is very weak.

3. Dose-response relationship: If cigarette smoking causes lung cancer, we would expect that smoking more cigarettes would increase the risk of lung cancer, which it does. In contrast, there appears to be no dose-response relationship between the number of vaccinations and the risk of developing autism.

4. Consistency: Have the findings that purported to show a relationship been replicated by other scientists, in other populations and at other times? If studies fail to consistently show the relationship, causation is very unlikely.

This is a critical point. One experiment or even a few experiments is NOT enough to determine causation. A large number of experiments that consistently show the same result is required. This is particularly important for vaccine rejectionists to note. The fact that a few studies claim to have shown that vaccination causes autism is meaningless when a very high proportion of studies show that there is not even a correlation between vaccination and autism.

5. Plausibility: In order to claim causation, you MUST offer a plausible mechanism. In the case of cigarette smoking, certain components of the smoke are known to cause damage to the cells inside the lungs, and cellular damage has been shown to lead to cancer. In contrast, no one has yet offered a plausible explanation for how vaccines “cause” autism. In fact, no one can even agree on the specific component that is supposedly responsible.

8. Specificity: Is Event A the only thing that leads to Disease B? This is the least important of the criterion. If it is present, it is a very powerful indicator of causation.

9. Coherence: The explanation of action must comport with the known laws of science. If the purported mechanism of causation violates the law of gravity, for example, then it isn’t acceptable.

What do Hill’s criteria look like in action?

In the case of cigarette smoking and lung cancer, for example, 8 out of 9 Hill’s Criteria are satisfied. In contrast, in the case of vaccines and autism, only 3, possibly 4 criteria are satisfied.

This is why we can say that the scientific evidence, including that presented by Helen Ratajczak, shows that vaccines do not cause autism.

Dr. Amy Tuteur does a wonderful job of comparing tobacco studies to autism/vaccine studies done by the industry. They are so similar it’s frightening. Nice to see this study by Dr. Ratajczak. Parents have known this stuff for years. If any of you Einsteins know how to do your own research, the actual study is easy to find.

Rebecca, thanks for posting @chris: That was my estimation too — it’s a theoretical paper using historical information, she did not collect data. Here is the original study, it doesn’t seem to be available in a traditional journal http://www.soundchoice.org/Images/Immunotoxicology_Ratajczak_2011_Review.pdf @Laura and chris, as the day-to-day science writer, please do tell me if you ever feel like i’m missing something.

“When vaccine manufacturers took the controversial mercury-based preservative thimerosol out of vaccines, they replaced it, in some cases, with human tissue.” Heather, this sentence from the above article is a prime example of poor science reporting. Human tissue did not replace thimerosol as a preservative (how would that even work?). And tissues are not found in vaccines. DNA fragments, yes, proteins, yes, whole tissues no.

And I think the following sentence shows where the author of this blog’s agenda lies, making a smart-ass remark about known potential side effects from vaccination: “University of Pennsylvania’s Dr. Brian Strom, a government advisor on vaccine safety, acknowledges that there is an accepted association between vaccines and brain damage (how reassuring) [...]”

And Heather, the review that was blogged about is available in a traditional journal, the Journal of Immunotoxicology. You can find it cited on PubMed. Which, for a review of unproven theories, is just an awful decision by the editor of that journal.

“And as far as can be established there is no autism in the unvaccinated group.” This statement is just blatantly untrue.

Follow the money. Can you imagine the financial implications if and when the CDC is forced to do a descriptive study comparing vaccinated and unvaccinated children and the rates of autism in these two groups? Informal descriptive studies show a HUGE correlation between vaccination and autism.

And don’t be fooled by all this double blind ethical research nonsense. There has never been a large scale study of tobacco in which people were randomly assigned to smoke for 25 years and then rates of lung cancer were compared. Descriptive studies compare people who DO smoke/vaccinate with people who DON’T and look at the difference in rates of lung cancer/autism.

The CDC refuses to do this study. I wonder why?

well said, MSFORTUNE. The mommy bloggers on Babble are really getting out of control with their anti-vaccination, pro natural birthing, anti-science paranoia. It’s ignorant and DANGEROUS. I’d like to see someone with an actual medical degree blog about childbirth and childcare issues here. Popping out a few kids doesn’t make you an expert in childbirth, just like the fact that I have teeth doesn’t make me a dentist.

So, those against vaccinations are perfectly willing to let their children contract and then possibly die from other diseases? You should also never drive around with your kid in a car because that is a very real way for them to die. And while we are at it, make sure you stick your kids in bubbles all day because accidents are a leading cause of death in children. Do you let your children fly in an airplane? Oh my, there’s a tiny chance they could be in a plane crash! Where does it end?

I haven’t found any good medical studies done by the medical community on the possible connection between vaccinations and autism. The studies I have found are garbage and do not prove the safety of vaccines. The medical community says that unless every child gets autism from a vaccine that there can be no connection. It is looking for a magic cause which is similar to the magic pill. If autism can be caused by accumulated toxins in the body, then is it “the straw that broke the camel’s back” that caused the autism? If it is accumulated toxins…. what caused the autism? The vaccine that was too much for that particular child to handle? Or the child’s body being unable to detoxify the vaccine? Or the pollutants in the environment that set up the child to be unable to detoxify the vaccine? And how about the reverse thinking. If every child that gets vaccinated is not fully protected from the disease that the vaccine is designed to protect that child from, then do we say that the vaccine is totally ineffective and no children should be vaccinated? Why are vaccines treated like something holy? Vaccines are innocent until proven guilty. When the increase in autism has climbed to such a high number of children being affected, the medical establishment talks about the vaccines as being so completely safe that it is better for the children to be vaccinated against an illness that they have almost no chance of ever getting. Vaccines are a huge social experiment. There have been no studies on the cumulative effect of injecting children with 30-60 vaccines. How can you talk science when there is no science?

Just a note from the writer: I have changed the title of this post to reiterate the fact that the study in question is a review of existing research, not new clinical research.

The government and medical establishment must now acknowledge that vaccines are a probable cause of autism, and that research needs to be urgently undertaken to ensure a safer childhood vaccination schedule that minimizes the risk of adverse reactions including autism.