Sometimes, even with a double-blind, placebo-controlled study, the worst side effects don’t show up until you try the medication in a larger population. It’s the “gold standard,” but it’s not perfect because nothing could be. For instance, a *real* test of the measles vaccine would be to give half the kids the vaccine, not give it to the other half, and then purposely expose both groups to the live measles virus. Obviously that’s unethical, but without that, how do we know it works? Animal studies, mostly.

I hear most vaccine studies use a placebo that is just all the ingredients in the vaccine except the virus. So if everyone gets reactions from the formaldehyde, for instance, that’s factored out because the “control group” had the same reaction. Only reactions that are from the virus itself will be recorded.

Meanwhile the opposing research isn’t necessarily better. For instance, that survey of unvaccinated kids had no control group. Instead of a control group, they just compared survey respondents with the surrounding population. That’s okay, but I’m sure the unvaccinated kids in the survey had many more things in common than just being unvaccinated: their parents had access to the internet, they heard of this study (probably through natural health blogs), etc. Any time you do a survey, you can’t help but select for people who are available and willing to do a survey.

It’s just important to remember that science does not deal in fact. (Surprised?) Science deals with *likely* fact. Some facts are extremely likely, to the point that we call them “scientific laws” because we are able to demonstrate them every single time we try. The human body is too complex to reach this kind of certainty, so we’re always trying new things and seeing what will happen. We’ve made tremendous advances in medicine in the last century, but we shouldn’t make the mistake of thinking that we now know all there is to know about the human body.

There is one problem which is hard to work around. Studies are done but not published if the results don’t match the goal of the company that paid for the study. I’ve even heard of studies being run several times until satisfactory results are achieved.

So how do you find the studies that aren’t published? One was is to check clinical trials.gov to see what is being studied. If you find a vaccine that was studied, where the the study was completed (or not completed but happened a while back) but you can’t find a published study, consider it a red flag.