Linqi Lu, Jiawei Liu, Sang Jung Kim, Ran Tao, Dhavan V. Shah, Douglas M. McLeod

Response efficacy information indicating the effectiveness of a recommended behavior in risk reduction is an important component of health communication. For example, many messages regarding COVID-19 vaccines featured numerical vaccine efficacy rates in preventing infections, hospitalizations, and deaths. While the relationship between disease risk perceptions and fear has been well established, we know less about the psychological factors involved in communicating vaccine efficacy information, such as response efficacy perceptions and hope. This study examines the effects of numerical vaccine efficacy information and message framing on vaccination intentions and their relationship to perceived response efficacy and hope, using a fictitious infectious disease similar to COVID-19. Findings suggest that communicating a high efficacy rate of the vaccine in preventing severe illness increased perceived response efficacy, which in turn boosted vaccination intention directly and indirectly through increasing hope. Also, fear about the virus was positively associated with hope about the vaccine. Implications of using response efficacy information and hope appeals in health communication and vaccination promotion are discussed.