Record numbers of parents are currently opting out of vaccinations for their children, partly due to the spread of discredited or unproven claims that link vaccines to autism. For public health officials scrambling to reassure the public about the safety of vaccines, new research out of the University of Erfurt in Germany offers some guidance about how to encourage parents to vaccinate their children.
According to researchers Niels Haase, Cornelia Betsch, and Frank Renkewitz, stories have a greater impact on parents’ perceptions of vaccine safety than do statistics.
In their study, published in the Journal of Health Communication: International Perspectives in June 2015, the researchers examined the effects of presenting participants with information about a fictional disease called “dysomeria” alongside a fictional study regarding the potential side-effects of the dysomeria vaccine. Participants were first told that “a study had observed [side effects from the vaccine] in about 20% of all the vaccination cases.” Participants then read one of two statements about the credibility of the study designed to make it seem more or less credible.
For instance, some participants read that “[s]ome time after its publication, the German Research Foundation and the Robert-Koch-Institute describ[e] this study as being poor with regard to the scientific methods employed and the data analysis.” Other participants read the statement that ““[s]ome time after its publication, the German Research Foundation and the Robert-Koch-Institute describ[e] this study as being exemplary with regard to the scientific methods employed and the data analysis.” A third control group read no additional statement.
Next, participants were asked to read “short narratives from an online forum, which described personal experiences with the dysomeria vaccination.” Some of the fictional accounts came from a neutral forum (“health-net.de”) while others came from an anti-vax site (“vaccination-harms.de”). The frequency with which negative stories about the vaccination came up in the accounts read was varied. Some participants saw negative accounts 35% of the time, while others saw them 85% of the time. This was done to determine whether seeing more anecdotal accounts of side effects encouraged participants to see the vaccine as riskier.
Participants were asked about their attitudes towards vaccines, the extent to which they based their views about the vaccine on the narrative stories or the statistics, and whether they thought the vaccination was risky.
The researchers found that reading the dysomeria vaccine narratives did encouraged participants to see the vaccine as riskier than the “official” risk statistics.” Furthermore, the information about the study’s credibility had little effect on the persuasiveness of the narratives. “Contrary to our expectations,” the researchers write, “informing participants that the statistical baserate [of side-effects as documented by the fictional study] was based on unreliable or very reliable data did not moderate the narrative bias.”
“Narrative evidence is a common feature of anti-vaccination websites,” the researchers explain. “Apparently, these reports affect individuals’ risk perceptions and vaccination intentions, irrespective of whether they were collected with a specific agenda in mind.”
However, “presenting the narratives in the context of an anti-vaccination forum led to a general decrease in vaccination risk perceptions” when compared to the participants who read the stories on a general health forum. That is, although both groups of respondents were influenced, people appear to have been swayed less by the stories when they were presented by anti-vaxxers.
“Fortunately, it appears that some anti-vaccination websites may inadvertently reduce this effect by stressing their agenda…Overall, the present research demonstrates once more how difficult it is to counter the biasing effect of narrative information.”
Journal of Health Communication: International Perspectives
Niels Haase, Cornelia Betsch, and Frank Renkewitz, University of Erfurt, Erfurt, Germany