Where are the Double Blind Placebo Controlled Randomized Trials about Vaccines

Have you ever heard that there are no double-blind, placebo-controlled randomized clinical trials for vaccines?

It isn’t true.

There are many double-blind, placebo-controlled randomized clinical trials that involved:

  • flu shots
  • pneumonia shots
  • HPV vaccines
  • potential HIV vaccines
  • malaria vaccines
  • rotavirus vaccines
  • Dengue vaccine
  • Staphylococcus aureus vaccine

That’s good, because double-blind, placebo-controlled randomized clinical trials are considered the “gold standard” when you do medical research.

“Placebo Control – A comparator in a vaccine trial that does not include the antigen under study. In studies of monovalent vaccines this may be an inert placebo (e.g. saline solution or the vehicle of the vaccine), or an antigenically different vaccine. In combined vaccines, this may be a control arm in which the component of the vaccine being studied is lacking.”

WHO on the Guidelines on clinical evaluation of vaccines: regulatory expectations

Tragically, many more folks got pneumonia and died if they got the saline placebo instead of the vaccine in this study.
Tragically, many more folks got pneumonia and died if they got the saline placebo instead of the vaccine in this study.

But do they all use a saline placebo?

No, not always, which typically leads anti-vaccine types to dismiss them outright and push anti-vaccine misinformation, including that they are never done.

It seems that they aren’t worried so much about the antigens in vaccines anymore (the Too Many, Too Soon argument), but are now more concerned about other vaccine ingredients. They will only be satisfied with a saline placebo, but they must miss the part about wanting the trial to be double-blinded, which gets harder to do if the placebo doesn’t look and “feel” like the vaccine.

And they miss the part that “not always” doesn’t mean never.

Gardasil is a good, recent example of a vaccine that had a double-blind, placebo-controlled (using a saline solution without an adjuvant) trial for safety.

Others vaccine trials use a saline control too, including efficacy and safety trials for a new recombinant, live, attenuated, tetravalent dengue vaccine (it worked and had a good safety profile), a malaria vaccine (a phase I dose escalation study), a universal flu vaccine, a Staphylococcus aureus vaccine, etc.

The Ethics of Placebo Use in Vaccine Trials

So why haven’t placebo control studies been done even more routinely then?

Why isn’t every vaccine on the immunization schedule or every combination of vaccines tested using a double-blind, placebo controlled study?

“Placebo use in vaccine trials is clearly acceptable when (a) no efficacious and safe vaccine exists and (b) the vaccine under consideration is intended to benefit the population in which the vaccine is to be tested.”

Placebo use in vaccine trials: Recommendations of a WHO expert panel

Of course, the answer is that in order to do this type of study, you would have to have a very good justification for leaving many of the kids unprotected and at risk for a vaccine-preventable disease.

Instead, as is discussed in the article “Current topics in research ethics in vaccine studies,” if a vaccine is “already in use in some other country or community which is more or less comparable to site where the trial is planned, that vaccine should be used as the comparator.”

So instead of a placebo, it is more common “to give another vaccine that provides comparable benefit against another disease, or more willingly, against similar disease caused by different agents.”

When can you use a placebo control?

The article states that “placebo controls are ethically acceptable when there is no proven vaccine for the indication for which the candidate vaccine is to be tested.”

But get educated and don’t be fooled, many double-blind, placebo-controlled randomized clinical trials have been done with vaccines.

What to Know About Placebo Use in Vaccine Trials

When it is ethical to do so, placebos have been used in vaccine trials, even saline placebos.

More on Placebo Use in Vaccine Trials

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