Vaccines are usually touted as one of the safest, most effective public health measures of all time.  One of the cornerstones of vaccine policy is that regardless of arguable risk, vaccines are very effective at preventing disease.

It must be said at the outset that I believe vaccines are effective to some degree (depending on how "effective" is defined), and do not count myself among those who believe that vaccines have had little or nothing to do with any overt disease declines.   However, I also think that like claims of safety, claims of vaccine-effectiveness are considerably overblown and understudied (more on these points in other columns).

And while there are many criticisms that can be made about such wide-reaching claims of effectiveness, some of which have been touched upon in previous Scandals, it is an argument often made against them being effective that I would like to take issue with at this time.

It is widely known that a certain percentage of vaccines fail, whether due to "primary vaccine failure" (i.e., the vaccine never worked in the first place) or "secondary vaccine failure" (waning immunity).  It is also true that outbreaks have occurred in highly vaccinated populations, including at least one population in which 100% were vaccinated.

Thus no one is arguing that vaccines are 100% effective.

So what happens when an outbreak occurs, and there are vaccinated involved?  Instead of noting that, of course, the vaccine doesn't always work, claims are made that this means the vaccine is ineffective.

And in a mostly vaccinated population, if most of the cases are vaccinated?  Well, instead of noting that, of course, in highly vaccinated populations most of the cases will usually have been vaccinated, there is almost a feeding frenzy over how ineffective the vaccine is.

It is to be expected that there will be more cases among the vaccinated in a highly vaccinated population.  But so what?  Was the vaccine effective most of the time, some of the time, or almost never? 

Making too much of the mere fact that there are outbreaks involving the vaccinated, drawing simplistic inferences about vaccine effectiveness without including critical information, detracts from legitimate discussion of vaccine effectiveness.

Vaccines are not perfect. The simple fact that outbreaks occur and the vaccinated can be counted among the cases, even if they constitute a majority of them, does not in and of itself constitute proof that vaccines are ineffective.  It just proves they are less than 100% effective.

And everybody already knows that.

There are viable arguments which can be made about and against vaccine-effectiveness.  But the mere fact that a vaccinated population, and in particular a highly vaccinated one, can result in cases among the vaccinated is not one of them. 

Sandy Mintz