Columbia, MO—Being on the front lines, pharmacists deal every day with vaccine refusal based on inaccurate risk-benefit assessment.
While counterintuitive to some, the solution seemed obvious to a group of researchers: provide more open communication about vaccine adverse effects to improve public trust and increase acceptance of immunization.
That’s not the way it worked out, however, according to a new study published in the journal Vaccine.
The University of Missouri–led study examined a proposal for more open communication about the Vaccine Adverse Event Reporting System (VAERS), a national vaccine safety reporting system that collects information about possible side effects that can occur after inoculation, and why the push to provide more information appeared to backfire.
VAERS, developed by the CDC, is available online. Study authors note that anyone can report possible adverse reactions to vaccines for any reason, giving it a broad range of information.
“One of the issues in vaccine acceptance is trust,” explained lead author Laura Scherer, PhD, associate professor of psychological sciences in the MU College of Arts and Science. “Individuals, parents and vaccine opponents lack trust that doctors and the government have done sufficient research to validate the safety of vaccines. By educating participants about the VAERS system, we thought that this might increase trust that the Centers for Disease Control are doing everything that they can to research and document vaccine harms.”
To explore that assumption, researchers used data on serious adverse events reported for the human papillomavirus vaccine in VAERS in 2013. To survey reactions from more than 1,200 participants to the VAERS reports, the study team divided participants into three groups:
• The first group was presented with the standard HPV vaccine statement that all patients receive prior to vaccination.
• The second group was given the same vaccine statement, as well as information about VAERS, which included data showing that out of approximately 10 million vaccinations, 24 individuals were reported to have been disabled and seven were reported to possibly have died as a result of their vaccinations.
• The third group received this VAERS information and also read the detailed reports of each event.
“Since anyone can report anything to VAERS for any reason, the VAERS reports contain incidents of serious adverse events that may not have anything to do with the vaccine,” Scherer pointed out. “We thought that by having people read the actual reports, they would see that there are very few reported serious events, and that the vaccine may not have even caused the event. Taken together, we felt this might make participants feel more assured that vaccines are safe—but in fact, what we found was the opposite.”
While participants who were educated about the VAERS system and who were given summary data about adverse events had slightly more vaccine acceptance compared to those who received the vaccine statement alone, results indicate that exposure to detailed incident reports significantly reduced vaccine acceptance and trust in the CDC's assurances that vaccines are safe.
Overall, according to the report, general information about the VAERS data slightly increased trust in the CDC and improved vaccine acceptance, but the specific VAERS reports negatively influenced both trust and acceptance.
“When participants read the incident reports, there was a marked reduction in their willingness to vaccinate—even though most participants believed the vaccines caused few or even none of the deaths,” Scherer explained in a University of Missouri press release. “Stories about vaccine harms can influence vaccine acceptance even when people don't completely believe them. This can potentially inform how people react to stories versus data about vaccine harms and provides a test of publicly available data on vaccine acceptance.
“It also means that the media should be very careful about propagating stories about vaccine harms when it is unclear that the vaccine was the cause.”
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