Testing the Efficacy of Attitudinal Inoculation Videos to Enhance COVID-19 Vaccine Acceptance: Quasi-Experimental Intervention Trial

"Relative to those who were not inoculated, inoculated participants showed significantly greater ability to recognize and identify rhetorical strategies used in misinformation, were less likely to share false information, and had greater willingness to get the COVID-19 vaccine."

Since the pandemic's beginning, a variety of COVID-19-related misinformation and disinformation has spread and been amplified online. Such inaccurate information can influence COVID-19 beliefs and protective actions; belief in vaccine misinformation is associated with lower vaccination rates and higher vaccine resistance. Attitudinal inoculation (or, simply, "inoculation") is a preventative approach to combating misinformation and disinformation that leverages the power of narrative, rhetoric, values, and emotion. This study tests inoculation messages in the form of short video messages to promote resistance against persuasion by COVID-19 vaccine misinformation, comparing the effectiveness of using facts versus narrative-rhetoric approaches.

The narratives used in this study were identified by analysing 6 months of content from 10 online channels of antivaccine or COVID-19 denialist propaganda. These channels took the form of Twitter accounts, amateur videos, documentaries, Facebook groups, blogs, and Instagram pages. From these media sources, the researchers created a list of 22 key narrative tropes and 16 rhetorical strategies and created a codebook. Narratives ranged from general claims that the COVID-19 vaccine could cause physical injury to the theory it was a bioweapon promoted by intelligence agencies. Some rhetorics framed their arguments along the lines of bodily autonomy by co-opting the language of women's reproductive rights, while others relied on audio-visual cues, such as nauseating colors and low-frequency sounds, to cue unease in their audience.

Based on the identification of the antivax narratives, the researchers developed 3 different inoculation messages: (i) a fact-based video, focused on countering false statistics about the science and safety of vaccines; (ii) a narrative/rhetoric-focused video that "prebunked" (countered potential misinformation by warning people against it before it is disseminated) common antivaccine misinformation strategies; and (iii) a hybrid video that tested a combination of factual rebuttal with narrative/rhetorical prebunking. They then designed three 30-second scripted inoculation videos, each of which contained a "microdose", a weakened example of manipulation that has been shown not to cause harm in a controlled research setting but that constitutes an "active threat" that lets people generate cognitive "antibodies" to misinformation. The idea is that such "antibodies" could allow viewers to discern more readily subsequent misinformation that makes use of similar flawed argumentation techniques.

The researchers conducted a quasi-experimental study with a pre-post intervention questionnaire and control group using between June 3 and 5 2021. Participants had not received a COVID-19 vaccine, were over the age of 18 years, and lived in the United States. In total, 500 US adults were recruited into 1 of 4 study arms, 1 for each type of inoculation video, plus a control group that received a video that described how to make a paper airplane. Participants were then asked a series of questions on their perceptions of the video. After watching the inoculation video, participants were shown a video stimulus that uses the manipulation techniques participants were alerted to in the inoculation video.

The study found significant effects across all 3 outcome variables comparing inoculation intervention groups to controls:

• In terms of the ability to recognise misinformation strategies (e.g., scary music, vague language), there was a significant intervention group effect (P<.001).
• For the outcome related to support for sharing the mis- and disinformation on social media, the intervention group main effect was statistically significant (P=.02).
• Intervention groups were more willing to get the COVID-19 vaccine compared to controls (P=.01).

The researchers point to the fact that the study was able to achieve these results in videos that were only 30 seconds in duration, which is consistent with short attention spans for online video consumption on social media and the length of many ads online. In fact, they propose that "online platforms are a viable place to disseminate these interventions to affect perceptions and behavior, because information on vaccine injury is viewed and spread on social media and exposure to online misinformation is associated with lower vaccination intentions....Social media platforms that may hesitate at the prospect of hosting inoculation videos containing a microdose of misinformation might be reassured that in the proper context of an inoculation message, these microdoses are vital to the overall discrediting of misinformation and disinformation."

Past studies into the relative efficacy of narrative/rhetoric compared to fact-based appeals have suggested that narrative approaches are more likely to be persuasive to viewers. However, this study did not find significant differences across the 3 active intervention groups, suggesting that the content of the intervention video (narrative/rhetoric, fact based, or hybrid) does not impact the effect of the intervention. This finding may be attributable to the nuanced differences in the scripts used, which might have been difficult to distinguish in such a short time frame.

The researchers suggest that videos that use attitudinal inoculation to combat COVID-19 vaccine misinformation should be tested in public health messaging campaigns to counter mis- and disinformation. Specifically, such videos should be tested with a broader audience beyond the United States and on social media platforms, such as YouTube and TikTok. "More research is needed to understand how videos with attitudinal inoculation perform when individuals are in a typical information consumption environment and faced with competing demands for attention."

In conclusion: "Online dissemination of these videos could be a viable strategy to increase vaccine uptake..."