HPV Vaccine

The HPV vaccine, which confers immunity to a sexually transmitted disease that causes cervical cancer, was engulfed in controversy from the day the CDC recommended it be administered universally to girls entering middle school. Why?

The obvious answer is the entanglement of the vaccine in clashing cultural understandings of gender roles, premarital sex, and parental autonomy.

But that answer, while not wrong, is incomplete.

The HBV vaccine also confers immunity to a sexually transmitted disease—hepatitis-b—that causes cancer. The CDC recommendation to add it to the schedule of universal childhood vaccinations provoked no controversy and was implemented by the vast majority of U.S. states.

During the years in which legislatures across the U.S. were convulsed in controversy over proposals to add the HPV vaccine to their mandatory vaccination schedules, the national HBV vaccination rate was consistently over 90%, the public-health target goal (Kahan 2013).

So why did the didn’t the HPV vaccine experience the same uneventful reception afforded the HBV vaccine? Why did the former, but not the latter, become enmeshed in cultural conflict?

This was the central question of a CCP study (Kahan, Braman, Cohen, Gastil & Slovic 2010).  That study, conducted shortly after the HPV vaccine was introduced, examined how individuals of diverse values would react to inforamtion about the vaccine.

The study found that individuals with opposing cultural values were predisposed to form contrasting impressions of the risks and benefits of the vaccine and that their differences only intensified when they were exposed to balanced pro- and con-arguments.

But the study found that individuals of all cultural outlooks were inclined to credit the  views of people they recognized as experts even when those experts supplied them with information that was contrary to the position those individuals were otherwise predisposed to believe.

This is a model, in effect, of how ordinary people identify valid science in the real world: because they know that experts are usually better situated to make sense of empirical data, people seek out those whom they recognize as having expertise and tend to defer to expert opinion.

Whether people of diverse values will agree or disagree about risks under these conditions, the study found, depends on what they observe when they turn to expert information sources. If they they are getting comparable forms of expert advice, individuals of diverse values can be expected to converge.

Where individuals observe that there is conflict on an issue, however, they will credit experts whose cultural values they tacitly perceive to be most like their own. This result can magnify polarization if individuals of diverse cultural orientations consistently observe the position they are predisposed to accept being espoused by experts whose values are like their own and the position they are predisposed to reject being espoused by experts whose values they are likely view as alien.

These findings model the contrasting conditions under which members of public learned of the HBV vaccine, on the one hand, and HPV vaccine, on the other.

The vast majority of parents encountered information about the HBV vaccine from their pediatricians, most of whom, regardless of their own cultural predispositions, counseled them to have their children vaccinated consistent with CDC guidelines.

But in the case of the HPV vaccine, the vast majority learned of the CDC proposal for universal vaccination from cable news and other partisan news sources reporting on a political debate over state legislation to make the vaccine mandatory for girls entering middle school.  That coverage featured dueling experts themselves conpicuously identified with opposing cultural groups, thereby creating in the world the conditions found to amplify polarization in the lab.

The reason the HPV vaccine entered public consciousness as a popular political issue rather than a personal medical one, moreover, was a consequence of marketing decisions made by Merck, Inc., the manufacturer of the HPV vaccine.

Normally, vaccines are added to the universal schedule of immunizations through guidelines issued by public health administrators operating outside the political realm. The HBV vaccine made its way onto the vast majority of state schedules by these means.

In the case of the HPV vaccine, however, Merck initiated a high-profile, nationwide political campaign to enact mandates legislatively.  It did so in an attempt to secure its status as supplier of the vaccine before FDA approval of a competing vaccine manufactured by SmithGlaxoKline.

The same goal motivated Merck to see “fast track” review of its vaccine, which necessitated that initiat approval be confined to girls only, since only females were vulnerable to cervical cancer, a disease serious enough to warrant fast-track procedures.

The spectacle of a nationwide debate over laws “mandating” an “STD shot” for “12 year-old girls” predictably excited political agitation—and thus assured that parents and others would form their first impression of the vaccine under conditions that the experimental model suggested were ones likely to generate cultural polarization.

Had the vaccine been introduced in the conventional manner (in which case, too, it would have been approved for boys and girls within three years), the HPV vaccine would have made its debut under the much less sensational, conflict-riven conditions that marked the advent of the HBV vaccine and that, according to the experimental model, would have generated cultural convergence.

The same conclusion is supported by Gollust, Dempsey et al. (2010).  In this experiment, researchers found that exposure to information about political conflict undermines the usual confidence that ordinary members of the public have in public health experts.

The career of the HPV vaccine illustrates the cost of failing to integrate the science of science communication with the procedures for generating and making use of decision-relevant science. The controversy was in fact foreseeable and foreseen, and the same methods that researchers used to analyze the conflict as it unfolded could easily have been used to forecast such conflict and to help public officials avoid it.


Gollust, S.E., Dempsey, A.F., Lantz, P.M., Ubel, P.A. & Fowler, E.F., Controversy undermines support for state mandates on the human papillomavirus vaccine, Health Affair 29, 2041-2046 (2010).

Kahan, D.M. A risky science communication environment for vaccines. Science 342, 53-54 (2013).

Kahan, D., Braman, D., Cohen, G., Gastil, J. & Slovic, P. Who fears the hpv vaccine, who doesn’t, and why? An experimental study of the mechanisms of cultural cognition. Law Human Behav 34, 501-516 (2010).

To return to the main page for this CCP Project, click here.

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