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Got this today on my facebook wall...

Alarming New Study: Unvaccinated Kids are Healthier

The study’s findings really make you wonder. Here’s some of the specifics:

  • Vaccinated children were more than three times as likely to be diagnosed on the Autism Spectrum (OR 4.3)
  • Vaccinated children were 30-fold more likely to be diagnosed with allergic rhinitis (hay fever) than non-vaccinated children
  • Vaccinated children were 22-fold more likely to require an allergy medication than unvaccinated children
  • Vaccinated children had more than quadruple the risk of being diagnosed with a learning disability than unvaccinated children (OR 5.2)
  • Vaccinated children were 300 percent more likely to be diagnosed with Attention Deficit Hyperactivity Disorder than unvaccinated children (OR 4.3)
  • Vaccinated children were 340 percent (OR 4.4) more likely to have been diagnosed with pneumonia than unvaccinated children
  • Vaccinated children were 300 percent more likely to be diagnosed with an ear infection than unvaccinated children (OR 4.0)
  • Vaccinated children were 700 percent more likely to have surgery to insert ear drainage tubes than unvaccinated children (OR 8.01)
  • Vaccinated children were 2.5-fold more likely to be diagnosed with any chronic illness than unvaccinated children

Are unvaccinated Kids are Healthier?

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    Do you happen to know what they mean by "vaccinated" and "unvaccinated"? Because there's a lot of different vaccines and several different suggested regiments. – fredsbend May 17 '17 at 2:47
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    Note that the "study" in question attracted criticism for major design issues (see points raised here for example), and was subsequently retracted by the journal. And then retracted again by another journal. – ff524 May 17 '17 at 4:40
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    Given the retractions (see comments by @ff524), is this claim even noteable? – DevSolar May 17 '17 at 7:26
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    This claim only says that parents that vaccinated their children pay more attention to their kids. – T. Sar - Reinstate Monica May 17 '17 at 13:06
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    I would go with a lessor "parents that don't vaccinate aren't having doctors help their kids" which is pretty close to a tautology, and seems to be the conclusion Oddthinking found. – user36688 May 17 '17 at 15:26
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Summary: The survey this article was based on was biased, poorly designed and poorly implemented. The conclusions cannot be trusted.


This study was examined by Orac who has been "checking in with and covering periodically ever since its inception in 2012, when antivaxers were fundraising for it."

The study has had a history of being retracted:

I’ve written about this study before. Hilariously, when it was published in its first form, the full study wasn’t published, only the abstract. Then the abstract was, in essence, retracted. Even more hilarious, it was a Frontiers journal, which is an even bigger dis because Frontiers journals are known for tending to be pay-to-publish predatory open access journals. If a Frontiers journal retracts your paper, it’s plenty bad indeed. It turns out that the manuscript had been reviewed by a chiropractor and a peer reviewer without expertise

The next day, Orac returned to announce it had been retracted again!

The first article complains of some minor issues: Apparent bias in the statement of purpose and having antivaccine organisation as the funding source.

He also criticised the misleading description and a biased sampling

Notice how Mawson claims that this is a cross-sectional study, when in reality it’s a survey targeting parents who homeschool. Of course, parents who choose to home school are not like your average parents. There are a lot of confounding factors that go along with home schooling, including the association between home schooling and antivaccine views. This association is very clear in the data, which show that 261 of the 666 subjects were unvaccinated.

He also describes the recruitment techniques as a source of bias too.

no effort was made to construct a representative sample.

In conclusion, he writes:

So what are we to make of the results of this study [...]?

Nothing. The bias and flaws in this study guaranteed no other result, particularly when you consider another confounding factor, namely that the parents of children who are fully vaccinated are very different in their health-seeking behavior than those whose children are unvaccinated. They tend to take their children to visit the doctor more regularly, which means that health disorders their children have are more likely to be diagnosed and treated. They’re also less likely to be seeing naturopaths and other alternative practitioners.


I looked for literature to bolstered Orac's unreferenced claim that "parents of children who are fully vaccinated are very different in their health-seeking behavior than those whose children are unvaccinated." My findings were mixed. I only found minor support for Orac's position.

This paper was useful to me in demonstrating some of the complexity behind the question - there has been a fair amount of research, and it has revealed geographic differenes.

This provided some fairly support for both Orac's statements about visiting doctors and also naturopaths and alternative practitioners:

Inhibitors [for parent vaccinating] included feeling alienated by or unable to trust the pediatrician, having a trusting relationship with an influential homeopath/naturopath or other person who did not believe in vaccinating, worry about permanent side effects, beliefs that vaccine-preventable diseases are not serious, and feeling that since other children are vaccinated their child is not at risk.

However, I don't want to overstate this - one of the "emerging themes" they discovered was:

there is overall trust in the pediatrician but a lack of trust in the information they provided about vaccines.

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    This, a thousand times this. It still blows my mind that people still don't get that the number of diagnosis isn't really a indicative of the disease in the population in general. This type of logic is like trying to evade cancer by avoiding doing things that can detect cancer. – T. Sar - Reinstate Monica May 17 '17 at 13:26
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    " the parents of children who are fully vaccinated are very different in their health-seeking behavior than those whose children are unvaccinated" - citation needed for that specific claim. – user5341 May 17 '17 at 15:35
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    I find there's two types of parents that don't vaccinate: the careless and the fearful. The fearful are extremely conscientious with their children's health, hence the decision not to vaccinate. I have met many fearful parents, but very few careless ones. If I remember right, the profile of a non vaccinating parent is upper middle class, educated, and very concerned with healthcare. – fredsbend May 17 '17 at 19:44
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    All this is to say they need a citation for "the parents of children who are fully vaccinated are very different in their health-seeking behavior than those whose children are unvaccinated", as @user5341 said, if their conclusion is that non vaccinating children are careless with health decisions. – fredsbend May 17 '17 at 19:45
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    @Oddthinking - sorry for imprecision, yes, I was specifically thinking "overall healthier". Re: bathtub curve, that's easy(ish) to correct for - you measure willingness to go to a doctor in a hypothetical situation instead of real visits. Less accurate (behavior!=mental model) but removes the problem you mentioned. – user5341 May 19 '17 at 13:46
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Are unvaccinated children healthier?

Not in the long run.


The quoted study compared the "health" of vaccinated children (in a rather questionable target group and using questionable methods, see Oddthinking's answer and ff524's comment) with the health of unvaccinated children... in a mostly vaccinated population.

It comes to the conclusion that...

...no evidence was found that vaccinated children were more protected against any so-called “vaccine-preventable diseases”. Children in both groups had roughly the same rates of infection from measles, mumps, Hepatitis A and B, influenza, rotavirus, and meningitis (both viral and bacterial).

This claims that being vaccinated has no significant benefit, and that is ludicrous.

Just picking the measles for an example, which are highly contagious. One shot of MMR vaccine is 93% effective, two shots are 97% effective. (Source: CDC)

The effect of vaccination is readily apparent from the significantly reduced number of cases after vaccination started:

Reported cases of measles in the USA, 1950-1993 (CDC)

The fact that the study you quoted did not find "evidence" of significant increases of measles infection among the unvaccinated children is the result of herd immunity, a well-researched and well-understood effect.

If enough members of a population are vaccinated, and (quoting the linked article)...

...it’s worth noting that over 95% of kids in America today are vaccinated...

...then the chances of getting into contact with the relevant pathogen is greatly diminished. Most people who contract the disease recuperate without passing it on, because most people are vaccinated against it.

If the claim is taken at face value, and used to justify not vaccinating children against vaccinable diseases, the percentage of vaccinated people will eventually fall below the threshold at which the vaccinated-against disease will spread (and, exceptional cases nonwithstanding, it will spread among the unvaccinated people mostly).

For measles, the threshold for herd immunity is estimated to be about 83-94%.

And this is not even taking into account the possibility of contracting a vaccine-preventable disease while abroad, or diseases where the pathogen is endemic to the environment (e.g. tetanus, rabies).


Post scriptum, the WHO estimates that measles vaccination alone has saved over 17 million lives since 2000. (WHO)

  • I totally agree with everything you say, but it doesn't refute the claim in the question. Antivaxers are essentially free-loaders, but that doesn't mean it doesn't work for them... – Benjol May 24 '17 at 11:51
  • @Benjol: Not in the long run. That's what I'm saying -- the sample size is too small. If they come into contact with a pathogen, they will fall sick, thwarting any benefit not vaccinating might have, real or imaginary. – DevSolar May 24 '17 at 11:53
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    Yes, my first reaction on seeing the question was "possibly, until they die" :) – Benjol May 24 '17 at 11:56
  • Re "Children in both groups had roughly the same rates of infection...", I strongly suspect that what is seen here is the effect of "herd immunity". That is, when a large enough fraction of the population has immunity to a contagious disease, it tends not to be passed on and become epidemic. See e.g. vaccines.gov/basics/protection/index.html So the unvaccinated kids that aren't getting those diseases are essentially freeloading off the rest of us. – jamesqf Jun 11 '17 at 17:33
  • @jamesqf: That is the gist of my answer, yes. – DevSolar Jun 11 '17 at 17:35

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