Vaccines: How do We Really Know What Happens?


Recently I taught one of my favorite topics to the First Years - vaccines. We discussed the science behind them, appropriate clinical use, and then we spent our clinical case time going through a family practice office visit with a mother who was uncomfortable about giving her 12-year-old son routine vaccinations. This was a real case, and my colleague described having to suppress her reactions to maintain professionalism. We wanted our students to walk through that same process, and by all measures it was an emotionally exhausting but very rewarding session. We took for granted that all of our students would be proponents of vaccination. We were mostly right, but not entirely. Within the context of a much longer email from a student, I received the following question:

“I've spoken to a few people who have opted out of vaccination. Their comment is: ‘But we just don't know what's in whatever we are injecting.’

From a science standpoint, yes, we "know" what's in it. But I also kind of agree -- do we really know what happens once we inject it?”

It got me thinking. Of course we as scientists know what happens down to the molecular level, but it suddenly struck me that perhaps almost no one – perhaps not even our clinical colleagues – realizes this. It suddenly made me think of my mechanic. I hand him my car keys, hang out in the waiting area talking everyone’s ear off, pay my bill, and then drive away fully confident that nothing terrible is going to happen to me because my car may not be safe. I myself have no idea what went on under the hood of my car, but I trust that he does. I always assumed that the same should happen with vaccines, but clearly I am missing something. Maybe that is the missing piece: the trust. Do most people need to know the intricate details of how vaccines work on a genes-and-molecules level? I shouldn’t think so, as that would be rather absurd. But I do need people to trust that we do. That is the piece that is missing, I think.

My response to my student was to describe the process of clinical trials, so that (s)he would feel comfortable with the idea that I wasn’t simply repeating a company line. We do know what happens. Here’s how:

(excerpted from my reply)

Vaccines are among the most extensively studied medical interventions that we have-they *HAVE* to be because of the ethics involved in setting up a clinical trial. I have no idea how much or how little exposure you may have had to human subjects research, but every study must be approved by something called an institutional review board ("IRB"). IRBs do not treat all studies equally by any stretch. A new drug meant to treat lung cancer can be given to a stage 4 (imminently terminal) patient more freely, and with a greater potential for side effects, than a new drug meant for minor pain relief in healthy people. There is a risk-benefit calculation made on a case-by-case basis. The end-stage cancer patient has very little to lose by even moderate side effects, whereas the otherwise healthy person treating a minor ailment risks a great deal with a moderate side effect. All that said, imagine the standards that must be met for a vaccine clinical trial involving healthy, pediatric patients that are preventing a future ailment that the child does not currently have. Sky-high, right? Before approval can be given for a clinical trial to occur, there has to be extensive laboratory work looking at how cultured and primary cells interact with the vaccine formulation (not only to exclude toxicity, but to view any unusual cellular responses relative to whatever liquid the vaccine antigen is suspended in alone). There also have to be numerous animal studies showing not only safety (lack of induced pathology, lack of cellular change, and lack of behavior change), but efficacy (the vaccine works as intended and protects against disease; this involves defining the correlates of immunity such as T cell and B cell reponses, cytokine levels, innate inflammatory markers, etc). If all of that is sufficient, then the trial moves ahead, wherein all of that same information is collected from hundreds to thousands of human patients. That said, I would argue that we do indeed know what happens once it is injected. I'm not saying that to be snarky in any way, mind you! I just suspect that very few people have any exposure to the logistics of clinical trials, and why we can rest assured that no poisons are being injected into babies. In addition, there is ample evidence to suggest that if there is an unacceptably high risk of side effects, the licensing companies often pull the vaccines from the market (LymeVax is an excellent example; RotaShield is another) simply because they don't want to get sued. On top of that, when the risk-benefit ratio shifts sufficiently so that the side-effect profile can no longer be justified in the face of dwindling risk, the recommendations change. I mentioned the oral polio vaccine numerous times in class, but elimination of routine smallpox vaccination is another strong example. I guess my point here is that, while one can't prove a negative (i.e., THERE ARE NO DETRIMENTAL EFFECTS EVER FROM VACCINES AND THERE NEVER WILL BE!!), there is overwhelming evidence than is typically presented that they are safe, effective, and instrumental tools of preventative medicine.

I am hopeful that this insight may be reassuring to any parents who may be worried about the safety of vaccines. Don’t trait a hypothetical risk for a real danger!