“Why, sometimes I’ve believed as many as six impossible things before breakfast.”

 – The Queen in Alice in Wonderland by Lewis Carroll

In its recent review of multiple vaccines and the infant immune system, in concluding that the “evidence favors rejection of a causal relationship between multiple immunizations and increased risk for infections”, the Institute of Medicine (IOM) chose to favor epidemiologic studies over animal studies.  This, in spite of the fact that they noted, “the biological mechanisms evidence regarding increased risk for infections is strong” (my emphasis).  And this, in spite of an earlier IOM complaint that among the "many gaps and limitations in knowledge bearing directly and indirectly on the safety of vaccines" they included "inadequate understanding of the biologic mechanisms underlying adverse events following natural infection or immunization" and that they “found few experimental studies published in relation to the number of epidemiologic studies published”. 

Research on biological mechanisms is generally considered a more rigorous scientific approach than epidemiological research.  And even though animal studies are always of conditional applicability to humans, they are still usually seen to provide a foundation upon which knowledge about human biological mechanisms can be built, particularly given widespread concern about human experimentation.

Epidemiologic studies, on the other hand, are thought to be the “poor cousins” to such research, even when the most rigorous standards are applied (i.e., randomized, placebo-controlled, double-blind, longitudinal studies).  Unfortunately, however, such standards are rarely put in practice, particularly in the case of vaccine safety and efficacy research, given that the only proper control group, the “never vaccinated”, is almost never used. 

In fact, by their own admission, the epidemiological studies reviewed by the IOM only compared those who received one vaccine to those who received one or more additional vaccines:  "The studies examined the effects of adding one vaccine to an existing immunization schedule, of one vaccine dose consisting of antigens from more than one infectious agent or strain of virus (e.g., DTP, OPV, or MMR), or several vaccines received at the same time."  So all these studies did was compare the vaccinated to the vaccinated.  If all it takes is one vaccine to cause such problems, multiple vaccination might not add additional risk.  If those studied had received even just one other vaccine in the past, that would mean everyone studied received multiple immunizations, so there might be no additional risk from additional multiple vaccinations.  In any case, the question has not been appropriately addressed.

However, even if the epidemiological evidence was strong against there being increased infections (and included many "gold standard" studies with never vaccinated children as controls), with the biological mechanism studies evidence strong for the existence of such a relationship, there would be no justification for rejecting the biological mechanism evidence in favor of epidemiological evidence.  At best, under such circumstances, no conclusions should be drawn.

Yet the IOM rejected studies of biological mechanisms in favor of epidemiological studies in their review.  Why?

Beyond that, the IOM failed to include in their review of the literature, a most relevant and important 1986 Science article, which I referred to in my 1993 IOM testimony, entitled “Two avirulent herpes simplex viruses generate lethal recombinants in vivo.”  In this study, mice were injected with two harmless herpes viruses that recombined in their bodies, killing 62% of them.

Infants and children receive many vaccines, sometimes alone, sometimes together.  Some vaccines are in themselves combinations, like MMR and DPT.  

If two harmless viruses can recombine in the body, what does that say about the potential for recombination of antigens derived from diseases thought serious enough to warrant preventing via vaccination and delivered to the body through them?

Moreover, when a 1986 study reported in a prestigious journal finds that two harmless viruses recombined in the bodies of mice and killed more than half of them and yet that study isn’t included in a review of the literature concerning the effects of multiple vaccinations on the immune system (a study which they were publicly told about almost 10 years ago), what does that say about the thoroughness and thoughtfulness of their report?

Sandy Mintz