Randomized Controlled Trials

It is widely acknowledged that when it is possible to randomize study participants, the RCT is the preferred design for evaluating the effectiveness and safety of health interventions. Data obtained from RCTs are often touted as the “gold standard” for clinical evidence, and results from a properly conducted clinical trial are considered to be of superior quality and reliability to evidence from most observational studies. The committee deliberately considered the form that an RCT of the immunization schedule could take and explored whether such a design would be both ethical and practical.

The critical advantage of the RCT is its ability to randomly assign participants to follow one of two or more different immunization schedules. Such a design would enable researchers to be reasonably certain that any observed difference in outcomes would be free of bias that could result from unequal allocation to treatment groups and would create reasonably comparable groups. The outcomes observed in a well-conducted RCT thus should accurately reflect an actual causal effect of treatment rather than results that could arise from population differences (Friedman et al., 2010).

Although it is well established that vaccines prevent a vast burden of disease among immunized as well as unimmunized or underimmunized people via community immunity, data suggest that some children continue to receive no vaccinations. One could argue that it would be ethical to recruit this population to an RCT comparing a group that receives the standard vaccination schedule with a group that receives no immunization. Because participants would be randomly placed in one of these study arms, at least half of the participating children, who otherwise would receive no vaccination, would receive all or part of the recommended immunization schedule. The other half would receive no benefit, except for a possible improvement in community immunity that would increase their chances of avoiding vaccine-preventable diseases. They would also avoid any hypothetical risk of receiving immunizations according to the ACIP-recommended schedule.

The committee considered and rejected this logic on the basis that any child, even the child of a parent who staunchly rejects vaccination, who is randomized to a no-vaccination arm is essentially consigned to an elevated risk of severe illness and even possible death should the child contract a vaccine-preventable disease. Moreover, should a child in the no-vaccination arm contract a preventable disease, the risk to other unprotected people in the community would increase. Randomization of such a child would also place the child’s pediatrician in the position of having to go against professional medical guidelines. Likewise, parents of intentionally unvaccinated children are unlikely to allow their children to be randomized to receive vaccines. Similarly, the committee believes that any study stipulating that



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