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Monday, August 14, 2017

The Vax War Goes On

At Vaccine, Mark Dredze and colleagues have an article titled "Vaccine Opponents’ Use of Twitter during the 2016 US Presidential Election: Implications for Practice and Policy."
These patterns show that those endorsing vaccine refusal are significantly more engaged with Mr. Trump than with other candidates. This engagement increased after the election. Given the increased energy of the vaccine refusal community, and early actions from the Trump administration, we may see policy proposals (including increased pressure on state governments from both federal and grassroots sources) aimed at addressing  erceived vaccine safety concerns. Even small changes can have consequences, since prevention of communicable diseases that impact children requires long-term, consistent effort.
At PLOS One,  Sara Pluviano, Caroline Watt, and Sergio Della Sala have an article titled Misinformation Lingers in Memory: Failure of Three Pro-vaccination Strategies."  The abstract:
People’s inability to update their memories in light of corrective information may have important public health consequences, as in the case of vaccination choice. In the present study, we compare three potentially effective strategies in vaccine promotion: one contrasting myths vs. facts, one employing fact and icon boxes, and one showing images of non-vaccinated sick children. Beliefs in the autism/vaccines link and in vaccines side effects, along with intention to vaccinate a future child, were evaluated both immediately after the correction intervention and after a 7-day delay to reveal possible backfire effects. Results show that existing strategies to correct vaccine misinformation are ineffective and often backfire, resulting in the unintended opposite effect, reinforcing ill-founded beliefs about vaccination and reducing intentions to vaccinate. The implications for research on vaccines misinformation and recommendations for progress are discussed.
From the article:
Our pattern of results thus confirms that there should be more testing of public health campaign messages. This is especially true because corrective strategies may appear effective immediately yet backfire even after a short delay, when the message they tried to convey gradually fades from memory, allowing common misconceptions to be more easily remembered and identified as true [25]. This is the case of one of the most frequently used corrective strategy employing the myths versus facts format, which often backfires because the simple repetition of the myth, though well-intended and necessary in order to contrast it with the available evidence, paradoxically amplifies the familiarity of that false claim making it seem even more believable and widely-shared [46]. This happens, at least partly, because people tend to mistake repetition for truth, a phenomenon known as the “illusory truth” effect [22, 23]. Familiarity appears as a key determinant of this effect; indeed, when something seems familiar is easier to process and one is more inclined to believe it [24], regardless of whether the statement is factually true or false [22, 47] or was initially rated as credible or questionable [48].
 Soumya Karlamangla and Sandra Poindexter report at The Los Angeles Times:
Even with a new law that has boosted kindergarten vaccination rates to record highs, hundreds of schools across California still have so many children lacking full immunization that they pose an increased risk of disease outbreaks, according to a Times analysis of state data.
At nearly 750 schools, 90% or fewer kindergartners had been fully vaccinated last year, the analysis found. Experts say the rate should be at least 95% to prevent the spread of highly contagious diseases such as measles.
California’s tougher inoculation law, known as SB 277, was approved in 2015 after a measles outbreak that originated at Disneyland. The law bars parents from citing religious or personal beliefs to excuse their children from immunizations, but some who already had such exemptions were allowed to keep them.
The rest of the unvaccinated children need a form signed by their doctor saying they had a medical reason not to get their shots.
In the school year that began last fall, the law’s first year, the number of kindergartners in California with medical exemptions tripled, the analysis found [from 991 to 2850]