Reported data on vaccines may not build public trust or adherence

"One of the issues in vaccine acceptance is trust," said Laura Scherer, 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."

Using data on serious adverse events reported for the Human Papillomavirus vaccine in VAERS in 2013, the researchers surveyed more than 1,200 participants' reactions to the VAERS reports. 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 said. "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."

Results showed that 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. However, exposure to detailed incident reports significantly reduced vaccine acceptance and trust in the CDC's declaration that vaccines are safe.

"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 said. "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."

The study, "Can the vaccine adverse event reporting system be used to increase vaccine acceptance and trust?" recently was published in the journal Vaccine. Scherer co-authored the study with Victoria Shaffer, associate professor of psychological sciences at MU and an assistant professor of health sciences in the MU School of Health Professions.