ABSTRACT
YouTube videos have been used to inform and misinform the public about the safety of vaccines related to health threats such as measles and COVID-19. Understanding how such videos can promote the sharing of accurate vaccine safety information is of the utmost importance if health researchers are to combat the spread of misinformation and encourage widespread uptake of vaccines. Through the lens of prospect theory, this study conducted a 2 (framing: loss v. gain) x 2 (evidence type: episodic v. thematic) x 2 (speaker expertise: expert v. non-expert) between-subject factorial experiment in which a sample of N = 400 US adults over the age of 18 recruited through MTurk were asked their intention to share vaccine safety information with others after watching a manipulated YouTube video. The results showed that loss framing was associated with perceived MMR severity which was, in turn, associated with the likelihood that participants would share MMR vaccine information with others, via any means. However, this process varied depending on the type of evidence delivered, and the expertise of the speaker. Results and limitations are discussed in the context of vaccine communication and social media.