Vaccine Risk Perceptions and Ad Hoc Risk Communication: An Empirical Assessment | Full Text Reports…
From the Social Science Research Network
Vaccine Risk Perceptions and Ad Hoc Risk Communication: An Empirical Assessment by Dan M. Kahan
Yale University – Law School; Harvard University – Edmond J. Safra Center for Ethics
January 27, 2014
CCP Risk Perception Studies Report No. 17
Based on survey and experimental methods (N = 2,316), 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 demographic, political, or cultural 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.
Based on these findings the Report recommends that government agencies, public health professionals, and other constituents of the public health establishment
Number of Pages in PDF File: 82
The report may be downloaded for free at the above URL
Some excerpts from the report
1. There is deep and widespread public consensus, even among groups strongly divided on other issues such as climate change and evolution, that childhood vaccinations make an essential contribution to public health. …
2. In contrast to other disputed science issues, public opinion on the safety and efficacy of childhood vaccines is not meaningfully affected by differences in either science comprehension or religiosity. …
3. The public’s perception of the risks and benefits of vaccines bears the signature of a gen- eralized affective evaluation, which is positive in a very high proportion of the population. …
4. Among the manifestations of the public’s positive orientation toward childhood vaccines is the perception that vaccine benefits predominate over vaccine risks and a high degree of confi- dence in the judgment of public health officials and experts. …
B. Normative and prescriptive conclusions
1. Risk communicators—including journalists, advocates, and public health professionals— should refrain from conveying the false impression that a substantial proportion of parents or of the public generally doubts vaccine safety.
2. Risk communicators should avoid resort to the factually unsupportable, polemical trope that links vaccine risk concerns to climate-change skepticism and to disbelief in evolution as evi- dence of growing societal distrust in science.
Remember, correlation does not equal causation!
And the selection of variables (as gun ownership) may be questioned by some…
Still, an interesting graph
Choosing the appropriate way to present risk statistics is key to helping people make well-informed decisions. A new Cochrane Systematic Review[abstract]*** found that health professionals and consumers may change their perceptions when the same risks and risk reductions are presented using alternative statistical formats.
Risk statistics can be used persuasively to present health interventions in different lights. The different ways of expressing risk can prove confusing and there has been much debate about how to improve the communication of health statistics.
For example, you could read that a drug cuts the risk of hip fracture over a three year period by 50%. At first sight, this would seem like an incredible breakthrough. In fact, what it might equally mean is that without taking the drug 1% of people have fractures, and with the drug only 0.5% do. Now the benefit seems to be much less. Another way of phrasing it would be that 200 people need to take the drug for three years to prevent one incidence of hip fracture. In this case, the drug could start to look a rather expensive option.
Statisticians have terms to describe each type of presentation. The statement of a 50% reduction is typically expressed as a Relative Risk Reduction (RRR). Saying that 0.5% fewer people will have broken hips is an Absolute Risk Reduction (ARR). Saying that 200 people need to be treated to prevent one occurrence is referred to as the Number Needed to Treat (NNT). Furthermore, these effects can be shown as a frequency, where the effect is expressed as 1 out of 200 people avoiding a hip fracture.
In the new study, Cochrane researchers reviewed data from 35 studies assessing understanding of risk statistics by health professionals and consumers. They found that participants in the studies understood frequencies better than probabilities. Relative risk reductions, as in “the drug cuts the risk by 50%”, were less well understood. Participants perceived risk reductions to be inappropriately greater compared to the same benefits presented using absolute risk or NNT.
“People perceive risk reductions to be larger and are more persuaded to adopt a health intervention when its effect is presented in relative terms,” said Elie Akl of the Department of Medicine, University at Buffalo, USA and first author on the review. “What we don’t know yet is whether doctors or policymakers might actually make different decisions based on the way health benefits are presented.”
Although the researchers say further studies are required to explore how different risk formats affect behaviour, they believe there are strong logical arguments for not reporting relative values alone. “Relative risk statistics do not allow a fair comparison of benefits and harms in the same way as absolute values do,” said lead researcher Holger Schünemann of the Department of Clinical Epidemiology and Biostatistics at McMaster University in Ontario, Canada. “If relative risk is to be used, then the absolute change in risk should also be given, as relative risk alone is likely to misinform decisions.”
Cochrane Reviews are “ systematic reviews of primary research in human health care and health policy. They investigate the effects of interventions (literally meaning to intervene to modify an outcome) for prevention, treatment and rehabilitation. They also assess the accuracy of a diagnostic test for a given condition in a specific patient group and setting.”
Rat Study Sheds Light on How Alcohol Affects Young Brain
Drinking at an early age may have long-lasting repercussions for decision-making, risk-taking
THURSDAY, March 17 (HealthDay News) — Based on the results of a new study conducted with rats, researchers say that kids who drink alcohol may have trouble with decision-making in adulthood.
Alcohol consumption during adolescence can change the perception of risk but does not affect how rewards are valued, the University of Washington researchers found.
The investigators studied decision-making in adult rats that had been given free access to alcohol when they were adolescents. The researchers measured changes in the neurotransmitter dopamine when the rats were offered rewards alone and also in response to cues predicting risky or certain outcomes.
“Dopamine is central to the way we process and evaluate rewards and is the primary target in the brain for virtually all abused drugs,” study author Jeremy J. Clark, an acting assistant professor of psychiatry and behavioral sciences, explained in a university news release.
In the rats, alcohol use during adolescence increased dopamine signaling to risky options but did not affect responses to rewards.
“Alcohol is corrupting the ability to make a good decision by altering the perception of risk. It doesn’t appear to be about the reward,” Clark said.
The study was published March 14 in the journal Proceedings of the National Academy of Sciences.***
- No Tonic for Tension: Stress Drinking Linked to Early Alcohol Use (livescience.com)
- Binge Drinkers May Risk Mood Disorders as Adults (integratedneuroscience.wordpress.com)
- Binge-drinking is in the genes: Scientists isolate brain reaction that makes us drink (dailymail.co.uk)