Mar 07 2014

Health of Vaccinated vs Unvaccinated

One of the new realities of social media is that old news can be dredged up and spread around. In this way old memes can keep coming back to life like the Terminator, and we have to kill them over and over again.

The antivaccine crowd, for example, has their narrative of conspiracy and evil and their cherry-picked factoids to support their narrative. In their world vaccines don’t work and are all bad all the time, and only corporate evil and public malfeasance can support them. They scour the internet for anything to support their beliefs, and then splash it around as if it’s news.

In this case, they have resurrected a terrible survey from 1992. The survey was conducted in New Zealand by the Immunization Awareness Society. Unsurprisingly, when this anti-vaccine group surveyed their own anti-vaccine members, they found a higher incidence of disease among vaccinated children compared to unvaccinated children.

The Free Thought Project declares this to “prove without a doubt” that unvaccinated children are healthier.  I don’t think they understand what the words “prove” or “doubt” mean.

Survey are, of course, highly problematic as scientific evidence. They are uncontrolled and subject to overwhelming confounding factors and bias. These can be minimized by being very rigorous in technique. No rigor is evident in this survey which relies upon a self-selected and biased population. We don’t even have access to the actual survey used, so really no conclusions can be drawn from the results.

By contrast, here is a published study that gathered information on over 17,000 subjects (compared to several hundred in the above survey), using a representative population, with full details disclosed. They found that the only health difference between vaccinated and unvaccinated children is that unvaccinated children had more vaccine-preventable diseases. That’s it. The study, however, only looked at allergies and other infections, but increases in allergies and infections is part of the anti-vaccine claim.

The second study quoted in the Free Thought article is also a survey, conducted by a German homeopath. Orac already deconstructed this survey, but here are the highlights: This is an online voluntary survey, so a self-selective group. Almost all respondents report that they use homeopaths, naturopaths, or chiropractors as their doctors and favor alternative medicine over mainstream medicine. There is no control group – the survey is just for the “completely unvaccinated.”

On other words – this survey is entirely worthless as scientific evidence. Also, ironically, the data shows an autism rate that is in line with the background rate in the general population. So even this crappy data cannot be used to argue for an association between vaccines and autism.


It is very telling that anti-vaccine groups and alternative medicine sites consistently reference terrible studies in support of their position.  The two surveys discussed above are essentially worthless, yet they are touted endlessly by anti-vaccine sites, and I am sure we will see them turn up over and over again.

Scientific evidence is never perfect, especially in a messy area like medicine. The best we can do is look objectively at all the available evidence and try to come to the most reliable conclusion we can.

If you have an agenda, however, there is always plenty of low-quality evidence to cherry pick. Unfortunately, it takes work and some familiarity with the research to recognize cherry picking for what it is.

Social media campaigns spreading lies and misinformation over and over again can therefore be effective, even when they rely upon outdated and terrible information.

All we can do on our end is to continue the game of whack-a-mole, and perhaps hope that the general public will become more critical and savvy over time.

270 responses so far