Testing Psychological Inoculation to Reduce Reactance to Vaccine-Related Communication

"Considering the polarized and politicized debate on vaccination, and the existence of vaccine mandates, it is possible that vaccination is perceived as a freedom-threatening topic. This could increase the risk that reactance inoculations are perceived as manipulative and render them less effective."



Vaccine-promoting communication can be perceived by some as infringing upon their autonomy to decide whether to vaccinate, possibly leading to the formation of negative attitudes toward vaccines and eventual vaccination refusal. Specifically, research has found that vaccine-promoting messages can elicit "state reactance" (i.e., negative emotions in response to a perceived threat to behavioural freedom), especially among individuals with high "trait reactance" (i.e., proneness to experiencing reactance). This study investigated whether inoculation against reactance - that is, forewarning individuals about potentially experiencing reactance - can reduce the effects of trait reactance on vaccination willingness.



Participants from Finland (n = 710) recruited through Facebook were presented with a short text asking them to imagine that a novel (fictitious) virus causing "green fever" is spreading across the world and that the disease can be serious to those infected. After this, participants randomly received either an inoculation text or no text. Those chosen to receive a text were presented with one of three leaflets including information about a fictitious vaccination campaign with different levels of threat to participants' freedom to choose to vaccinate or not (low, medium, or high). The inoculation read as follows: "The following texts may contain strong language. Some may feel that the text is an attempt to limit their freedom to make their own decisions. Try not to let this affect your judgment. The message of the text may be good and contain important information, although it is presented in a way that may arouse negative feelings, such as anger."



To measure how much state reactance the leaflet elicited, the researchers used the question and the item "frustrated" from the Epistemic Emotions Scale, along with two additional items: "angry" and "irritated". Trait reactance was measured with the Hong Psychological Reactance Scale. Willingness to get vaccinated with the fictitious vaccine was measured with the question, "How willing would you be to get the vaccine mentioned in the leaflet if it were real?" Vaccine attitudes were measured with the 5C scale, which consists of five statements measuring vaccine confidence, convenience, complacency, calculation, and collective responsibility.



The results showed that inoculation against reactance was ineffective in reducing state reactance to the message and preventing the negative effects that trait reactance had on vaccination willingness and receptiveness to vaccine information. Post-hoc analysis even suggested that the inoculation backfired for some participants, as the inoculated participants were more likely than the uninoculated ones to lower their vaccination willingness after receiving information about the vaccine. High-reactant individuals were less willing to get vaccinated than low-reactant ones, especially at high freedom threat. Conversely, high freedom threat resulted in increased vaccination willingness among low-reactant individuals.



In reflecting on the findings, the researchers note that reactance can have consequences that extend beyond willingness to accept the targeted vaccine, as experimental research has found that vaccine-promoting messages that induce state reactance lower intentions to accept other (unmentioned) vaccines and decrease willingness to engage in other health-protecting behaviours. They suggest that future research should investigate how to balance messaging to maximise vaccine uptake. In particular, solutions are needed to mitigate the negative effects of high trait reactance on the effectiveness of vaccination campaigns without sacrificing the positive effects that vaccine recommendations have for low-reactant individuals.