Who fears childhood vaccines and why? Research report & project

Just posted new report, Vaccine Risk Perceptions and Ad Hoc Risk Communication: An Empirical Assessment. It presents the results of a  large (N = 2300) national study of the public’s perception of the risks and benefits of childhood vaccines. The study also includes an experimental component that examines how those perceptions are influenced by “ad hoc” risk communication —  information from popular sources that feature empirically uninformed claims about the extent, nature, and consequences of public concern about vaccine risks (there’s very little concern to speak of, and views do not vary meaningfully across political or cultural groups).

The Report is part of a new CCP project on “Protecting the Vaccine Science Communication Environment.” The project has its own page, which explains the project mission and links to various content.

I’ll likely be featuring bits & pieces of the Report in the blog over the next  couple weeks.  I’m eager not merely to alert potentially interested readers that it is available but also to solicit comments, questions, and proposals for additional analyses.  Indeed, I anticipate issuing “updates” to the Report based on such feedback.

Here is the Report “Executive Summary”:

Executive Summary

This Report presents empirical evidence relevant to assessing the claim—reported widely in the media and other sources—that the public is growing increasingly anxious about the safety of childhood vaccinations. The Report presents two principal findings: first, that vaccine risks are neither a matter of concern for the vast majority of the public nor an issue of contention among recognizable subgroups; and second, that ad hoc forms of risk communication that assert there is mounting resistance to childhood immunizations themselves pose a risk of creating misimpressions and arousing sensibilities that could culturally polarize the public and diminish motivation to cooperate with universal vaccination programs.

The basis for these findings was a study of a demographically diverse sample of 2,300 U.S. adults. In a survey component administered to a nationally representative 800-person subsample, the study found a high degree of consensus that vaccine risks are low and their benefits high. These perceptions, the data suggest, reflect the influence of a pervasively positive and widely shared affective orientation toward vaccines. This same affective orientation is reflected in widespread support for universal immunization and expressions of trust in the judgment of public health officials and professionals.

There was a modest minority of respondents who held a negative orientation toward vaccines. These respondents, however, could not be characterized as belonging to any recognizable subgroup identified by demographic characteristics, religiosity, science comprehension, or political or cultural outlooks. Indeed, groups bitterly divided over other science issues, including climate change and human evolution, all saw vaccine risks as low and vaccine benefits as high. Even within those groups, in other words, individuals hostile to childhood vaccinations are outliers.

In an experimental component administered to the entire sample, the study examined the impact of media and other reports that warn of escalating public concern over vaccine safety. Such information induced study participants to substantially underestimate vaccination rates and to substantially overestimate the proportion of parents invoking “exemptions” to universal immunization policies. This result is troubling because existing research shows that the motivation to contribute to collective goods, such as the herd immunity conferred by mass vaccination, declines when members of the public perceive that others are refusing to contribute. In contrast, exposure to a communication patterned on a typical CDC press statement induced subjects to form estimates much closer to actual U.S. vaccine rates (90% or above for over a decade) and of the proportion of children receiving no vaccinations (1%).

The experiment also examined the effect of information patterned on popular sources that link the belief that vaccines cause autism to disbelief in evolution and climate change. Among study subjects exposed to this information, perceptions of vaccine risks showed signs of dividing along the same cultural lines that inform disputes over highly contested societal issues, including the dangers of climate change, the consequences of drug legalization, and the impact of educating high school students about birth control. This result is also troubling: group-based conflicts are known to create strong psychological pressures that interfere with the normally reliable capacity that members of the public use to recognize valid decision-relevant science. This very dynamic is thought to have affected acceptance of the HPV vaccine.

Based on these findings the Report offers a series of recommendations. The most important is that the public health establishment play a more active leadership role in risk communication. Governmental agencies and professional groups should (1) promote the use of valid and appropriately focused empirical methods for investigating vaccine-risk perceptions and formulating responsive risk communication strategies; (2) discourage ad hoc risk communication based on impressionistic or psychometrically invalid alternatives to these methods; (3) publicize the persistently high rates of childhood vaccination and high levels of public support for universal immunization in the U.S.; and (4) correct ad hoc communicators who misrepresent vaccination coverage and its relationship to the incidence of childhood diseases.

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